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1.	Arman, M. M., et al. (författare) Synchrotron radiation X-ray absorption fine structure and magnetization improvement of A-site Ce3+ doped LaFeO3 2020 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; 513 Tidskriftsartikel (refereegranskat)abstract Synchrotron radiation (SR) is an interesting tool for probing the properties of the matter in various domains such as nanotechnology, energy materials, catalysis and the cultural heritage. Herein, we synthesized nanomultiferroic samples La1−xCexFeO3 (0.00 ≤ x ≤ 0.15) using auto combustion method and glycine as a fuel. The magnetic behavior was studied and interrelated with the results of synchrotron radiation X-ray absorption fine structure (XAFS) spectroscopy for better understanding the compositional-dependent fine local structures of A-site (Ce3+) doped LaFeO3 nanomultiferroic. The crystallinity and phase formation of the samples of perovskite structure were confirmed by XRD technique. Field emission scanning electron microscopy (FESEM) revealed the formation of homogenous porous morphology in the prepared nanomultiferroic. The collected XAFS signals at Fe K- edge (7112 eV) and La L3- edge (5483 eV) are analyzed, fitted, and refined in both the XANES and EXAFS regions. All obtained results are correlated in order to help in the interpretation of the magnetic character of nanocrystallite La1−xCexFeO3 (0.00 ≤ x ≤ 0.15). It was observed that there is a magnetization improvement in Ce3+ doped LaFeO3 samples where the molar magnetic susceptibility (χM) increased upon Ce3+ doping. The characteristics of the improved magnetic nanomultiferroic hand in hand with its distinguished morphology recommend it in multifunctional applications such as catalysts and/or γ-radiation dosimetry purposes.
2.	Barwal, Vineet, et al. (författare) Spin gapless semiconducting behavior in inverse Heusler Mn2-xCo1 +/- xAl (0 x 1.75) thin films 2021 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 518 Tidskriftsartikel (refereegranskat)abstract We correlate the structural, electrical, and magnetotransport properties of co-sputtered Mn2-xCo1?xAl full Heusler alloy thin films (0 x 1.75) in terms of Co/Mn concentration variation concerning the spin gapless semiconducting (SGS) behavior. The alloy thin films are found to stabilize in B2 order for near stoichiometric films, i.e. (x = 0 and x = 1), with the gradual change in the ordering and lattice parameter through Mn concentration variation. Magnetization measurements in Mn2-xCo1?xAl thin films reveal the ferromagnetic and ferrimagnetic character for x = 1.75, 1.5, 1.25 & 1, and x = 0, 0.5 & 0.75, respectively. The longitudinal resistivity measurement revealed that the films exhibit semiconducting behavior with a change in sign of the temperature coefficient of resistance with temperature. The anomalous Hall conductivity values for the Mn2-xCo1?xAl thin films are extracted from the Anomalous Hall effect (AHE) measurements. The non-saturating positive MR (linear in H) is being reported for the first time in the Mn2CoAl thin films. The value of the AHE coefficient and positive MR together serve as a piece of experimental evidence for the SGS character in the thin film. The SGS behavior becomes predominant at higher Mn concentration. Highly resistive thin films with ferromagnetic (ferrimagnetic) character in Co2MnAl (Mn2CoAl) could be beneficial for semiconductor spintronics, where we need a good resistive element to match up with Silicon base substrate.
3.	Barwal, Vineet, et al. (författare) Structural and magneto-transport properties of co-sputtered MnAl thin films 2020 Ingår i: Journal of Magnetism and Magnetic Materials. - : ELSEVIER. - 0304-8853 .- 1873-4766. ; 503 Tidskriftsartikel (refereegranskat)abstract We report the structural and magneto-transport properties of co-sputtered MnAl alloy thin films grown on Si (1 0 0) at various substrate temperatures (T-s) ranging from room temperature to 500 degrees C. Analyses of the X-ray diffraction and DC-Magnetization data reveal that as the T-s of the films is changed, the volume fraction of ferromagnetic tau-MnxAl100-x (50 < x < 60) metastable phase retained in the films changes from 3.7 to 9.5% and the remaining fraction comprises of non-magnetic beta-MnAl and gamma(2)-phases. The temperature-dependent longitudinal resistivity variation demonstrates a semi-metallic nature in all these films. The temperature dependence of Hall Effect data further corroborates this semi-metallic behavior. The magnetoresistance (MR) response of these films is measured in the range of 10-300 K, both in the in-plane as well as out-of-plane magnetic field configurations. The out-of-plane MR is significantly larger than in-plane MR due to electron-hole compensation (which stems from mull-band effects) which is discussed further by plotting the Kohler's plot for the thin films.
4.	Bulbucan, Claudiu, et al. (författare) Cr-substituted Fe3O4 nanoparticles : The role of particle size in the formation of FexO sub-domains and the emergence of exchange bias 2023 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; 570 Tidskriftsartikel (refereegranskat)abstract Here we study the influence of particle size on the formation of antiferromagnetic FexO subdomains and the emergence of exchange bias in novel ferrimagnetic Cr-substituted Fe3O4 nanoparticles generated using an aerosol technique based on spark ablation. Cooling in an applied magnetic field across the Néel temperature of the FexO subdomains results in significant shifts in the hysteresis loops, which decrease in magnitude with the particle diameter for the two large systems (D≈20nm&D≈40nm), whereas only minor exchange fields are observed for the smallest system (D≈10nm). The reduced exchange bias is attributed to the metastable FexO's lower volume fraction and size due to a facile transformation into the thermodynamically stable (Fe,Cr)3O4 phase with decreasing particle diameter.
5.	Burkhardt, C., et al. (författare) An overview of Hydrogen assisted (Direct) recycling of Rare earth permanent magnets 2023 Ingår i: Journal of Magnetism and Magnetic Materials. - : ELSEVIER. - 0304-8853 .- 1873-4766. ; 588:B Tidskriftsartikel (refereegranskat)abstract Rare Earths (RE) permanent magnets are essential components for Europe’s successful green and digital transition However, the entire value chain of RE magnetic materials depends on imports, which are highly vulnerable in current global supply chain models. To mitigate this situation, EU Regulation plans that at least 15 % of the EU’s annual consumption of permanent magnets should be covered by recycling capacities by 2030. Researchers in the EU H2020 project SUSMAGPRO consortium have shown that hydrogen can be used as a very efficient recycling method to extract NdFeB magnet powder from various EOL Components in the IP protected Hydrogen-based Processing of Magnet Scrap (HPMS). On exposure to hydrogen the sintered NdFeB magnets break down into a friable, demagnetised, hydrogenated powder containing an interstitial hydride of Nd2Fe14BHX (10 mu m) and smaller particles (<1 m) from the grain-boundary phase NdH2.7. This process delivers a sustainable source of magnetic material for the production of sintered, polymer bonded and metal-injection moulded magnets. The paper will present numerous results along the whole value chain of magnet recycling, including automatic dismantling of magnet containing products, magnets extraction, HPMS recycling, production of recycled magnets and demonstrator testing. It will also discuss best practices and bottlenecks of the processes as an outlook for successful design-for-recycling of future applications.
6.	Dias, P. F., et al. (författare) Residual entropy, bicriticality, and tricriticality in the frustrated Ising model on the honeycomb lattice 2024 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 604 Tidskriftsartikel (refereegranskat)abstract Phase transitions and thermodynamic properties of the frustrated J1-J2-J3 Ising model on the honeycomb lattice are investigated by using the cluster mean-field theory and Monte Carlo simulations. We investigate the role of thermal fluctuations in the model with ferromagnetic exchange interactions between first and third neighbors and antiferromagnetic second-neighbor couplings. Our findings indicate that these competing interactions can lead to three forms of long-range order and different scenarios concerning phase transitions. For weak third-neighbor interactions, strong frustration effects bring the ordering temperature to absolute zero and lead to residual entropy. Moreover, thermodynamic signatures of frustration such as a round maximum in the specific heat can be found above the ordering temperature. The model also exhibits continuous and discontinuous order–disorder phase transitions, hosting tricriticality for weak and moderate strengths of third-neighbor couplings. At strong enough third-neighbor couplings, discontinuous order–disorder phase transitions are suppressed and a bicritical point can be observed. Our findings are discussed in connection with recent experimental results for Ising spin systems on the frustrated honeycomb lattice, including van der Waals magnets.
7.	Dobrynin, A. N., et al. (författare) On the origin of positive exchange bias and coercivity enhancement in proximity to the blocking temperature 2021 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 520 Tidskriftsartikel (refereegranskat)abstract Magnetic properties of two oxidised Co thin films prepared by different sputtering techniques are analysed. Exchange bias (EB) blocking temperatures (T-B) of the samples were found to be 50 K different due to difference in grain sizes of antiferromagnetic CoO. In proximity to T-B the EB changes its sign from negative to positive. This positive EB behaviour is strikingly similar for the two samples with the exception of its position on the temperature scale. A computational model, taking into account temperature dependence of the antiferromagnet's magnetocrystalline anisotropy and its sublattices' magnetisation, reproduces positive EB in proximity to T-B. This happens when a significant fraction of antiferromagnetic entities becomes involved in magnetisation reversal, and there is antiferromagnetic exchange coupling between those entities. The coercivity enhancement, accompanying positive EB, is due to anisotropy energies of the reversible antiferromagnetic entities contributing to the ferromagnetic layer's energy barrier. The model suggests that in order for the two samples to have identical positive EB behaviour, the reversible antiferromagnetic entities should represent individual spins.
8.	Eberbeck, D., et al. (författare) Magneto-structural characterization of different kinds of magnetic nanoparticles 2023 Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853. ; 583 Tidskriftsartikel (refereegranskat)abstract Using well-established measurement techniques like transmission electron microscopy (TEM), dynamic light scattering (DLS), small and wide angle X-ray scattering (SAXS, WAXS), susceptometry, and magnetorelaxometry, the distribution of the physical and magnetic size (magnetic moments) and magnetic anisotropy of a variety of structurally different magnetic nanoparticle samples (MNPs) is analyzed and compared. A term which accounts for the presence of weak magnetic areas (WMAs) within the MNPs was introduced to the widespread analysis model for M(H) data, enabling a consistent interpretation of the data in most of the systems. A comparison of the size distributions as obtained for the physical and the magnetic diameter suggests a multidomain structure for three single core systems under investigation, in all probability evoked by the presence of a wustite phase, as identified by WAXS. Analyzing the relationship d < dm < dc between the average single core diameter d, the effective magnetic (domain) size dm and the cluster diameter dc quantitatively, two qualitatively different magnetic structures in multicore MNP (MCMNP) systems were identified: (i) The magnetic moments of single cores within the MCMNP of fluidMAG tend to build flux closure structures, driven by dipole–dipole interaction. (ii) The magnetic behavior of Resovist® was attributed to the presence of domain sizes of about 12 nm within MCMNP, exceeding the single core diameters of 5 nm. Thereby, WAXS revealed a bimodal crystallite size distribution suggesting a crystallite merging process within the MCMNP. The value of the effective magnetic moment of these MCMNP could be explained within the presented “random moment cluster model” (RMCM). We conclude that the combination of physical and magnetic structure parameters obtained from complementary measurement methods allows a reliable assessment of the magnetic structure of single and multicore MNPs.
9.	Gas, Katarzyna, et al. (författare) Magnetic properties of wurtzite (Ga,Mn)As 2021 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 533 Tidskriftsartikel (refereegranskat)abstract Here we report on detailed studies of the magnetic properties of the wurtzite (Ga,Mn)As cylindrical shells. Ga0.94Mn0.06As shells have been grown by molecular beam epitaxy at low temperature as a part of multishell cylinders overgrown on wurtzite (Ga,In)As nanowires cores, synthesized on GaAs (111)B substrates. Our studies clearly indicate the presence of a low temperature ferromagnetic coupling, which despite a reasonably high Mn contents of 6% is limited only to below 30 K. A set of dedicated measurements shows that despite a high structural quality of the material the magnetic order has a granular form, which gives rise to the dynamical slowdown characteristic to blocked superparamagnets. The lack of the long range order has been assigned to a very low hole density, caused primarily by numerous compensation donors, arsenic antisites, formed in the material due to a specific geometry of the growth of the shells on the nanowire template. The associated electrostatic disorder has formed a patchwork of spontaneously magnetized (macrospin) and nonmagnetic (paramagnetic) volumes in the material. Using high field results it has been evaluated that the total volume taken by the macrospins constitute about 2/3 of the volume of the (Ga,Mn)As whereas in the remaining 1/3 only paramagnetic Mn ions reside. By establishing the number of the uncoupled ions the two contributions were separated. The Arrott plot method applied to the superparamagnetic part yielded the first experimental assessment of the magnitude of the spin-spin coupling temperature within the macrospins in (Ga,Mn)As, TC = 28 K. In a broader view our results constitute an important contribution to the still ongoing dispute on the true and the dominant form(s) of the magnetism in this model dilute ferromagnetic semiconductor.
10.	Ghorai, Sagar, et al. (författare) Effect of reduced local lattice disorder on the magnetic properties of B-site substituted La0.8Sr0.2MnO3 2021 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 529 Tidskriftsartikel (refereegranskat)abstract Disorder induced by chemical inhomogeneity and Jahn-Teller (JT) distortions is often observed in mixed valence perovskite manganites. The main reasons for the evolution of this disorder are connected with the cationic size differences and the ratio between JT active and non-JT active ions. The quenched disorder leads to a spin-cluster state above the magnetic transition temperature. The effect of Cu, a B-site substitution in the La0.8Sr0.2MnO3 compound, on the disordered phase has been addressed here. X-ray powder diffraction reveals rhombohedral (R-3c) structures for both the parent and B-site substituted compound with negligible change of lattice volume. The chemical compositions of the two compounds were verified by ion beam analysis technique. With the change of electronic bandwidth, the magnetic phase transition temperature has been tuned towards room temperature (318 K), an important requirement for room temperature magnetic refrigeration. However, a small decrease of the isothermal entropy change was observed with Cu-substitution, related to the decrease of the saturation magnetization.
11.	Grishin, Alexander M., et al. (författare) Crystallization kinetics and magnetostriction properties of amorphous Fe 80-x Co x P 14 B 6 metallic glasses 2020 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 512 Tidskriftsartikel (refereegranskat)abstract Formation mechanism and crystallization kinetics were studied in series of rapidly solidified metallic glasses Fe80- xCoxP14B6 with x = 23, 25, 28, 32, 35 and 40 at.%. As soft magnetic materials, they surpass characteristics of commercial Iron-Nickel Metglas® 2826 alloy: differential permeability of as quenched amorphous ribbons is of about 110,000, the saturation induction μoMs = 1.45–1.5 T, coercive field as low as 4 A/m, Curie temperature above 700 K, and significantly higher thermal stability. Isochronal and isothermal differential scanning calorimetry was employed to record the latent heat developed during crystallization. For both regimes, X-ray diffraction revealed two immiscible bcc α-FeCo and bct (Fe,Co)3(P,B) phases that crystallize from completely miscible amorphous glass matrix. Theoretical description of observed kinetics of crystallization process was convincingly accomplished within Kolmogorov-Johnson-Mehl-Avrami model. Enhanced thermal stability of iron-rich Fe80- xCoxP14B6 glasses that crystalize at higher temperatures relies upon higher crystal/glass interfacial energy.
12.	Guillou, F., et al. (författare) Metamagnetic transition, magnetocaloric effect and electronic structure of the rare-earth anti-perovskite SnOEu3 2020 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 501 Tidskriftsartikel (refereegranskat)abstract Rare-earth anti-perovskites with oxygen are an interesting magnetic materials family at the boundary between intermetallics and oxides, they however remain largely unexplored. Here, magnetic and heat capacity investigations, as well as density functional theory (DFT) calculations, were carried out on SnOEu3. At low magnetic field (B <= 0.5 T), a Neel temperature separates antiferromagnetic and paramagnetic phases at 31 K. When applying higher magnetic field below the Neel temperature, successive transformations toward a ferromagnetic state via a number of intermediate canted magnetic structures are observed and are associated with only modest latent heat and transition entropy. High-pressure magnetic measurements confirm the stable divalent state of Eu up to 1.05 GPa. A direct magnetocaloric effect progressively increases with applied magnetic field above the Neel temperature, reaching -16 J kg(-1) K-1 for Delta B = 7 T. On the other hand, the inverse magnetocaloric effect of the field-induced transition below T-N saturates at similar to+ 5 J kg(-1) K-1. DFT calculations support magnetic instabilities observed experimentally in SnOEu 3 and reveal an unusual exchange mechanism and band topology near the Fermi level.
13.	Hait, Soumyarup, et al. (författare) Comparison of high temperature growth versus post-deposition in situ annealing in attaining very low Gilbert damping in sputtered Co2FeAl Heusler alloy films 2021 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 519 Tidskriftsartikel (refereegranskat)abstract In this work, a detail study on the effectiveness of high substrate temperature (TS) during deposition versus in situ annealing of the films at high temperature (TA) after sputtering at room-temperature is compared with an objective to obtain Heusler alloy thin films of Co2FeAl (CFA) having optimally low alpha int (with an upper bound of 1.75 & times; 10-3) and 12-17% smaller MS by employing ion beam sputtering technique and Si(100) as substrates for current induced magnetization switching application. In each of the two series of CFA films, prepared with different choice of TS and TA (lying in 300-773 K range) were explored for optimally tailoring their structural, static and dynamic magnetization properties. Structural study revealed that although all the CFA films were polycrystalline but the post-deposition annealed films were structurally optimal with higher density (6.36 +/- 0.09 g/cm3) and lower interface roughness (0.48 +/- 0.03 nm) compared to the CFA films grown at high TS (6.23 +/- 0.06 g/cm3, 0.61 +/- 0.01 nm). In plane field-angle dependent longitudinal magneto optical Kerr effect (LMOKE) study revealed the existence of a coupling between the weak uniaxial and biaxial magnetic anisotropies present in these films, attributed to the employed deposition geometry. Ferromagnetic resonance (FMR) spectroscopy measurements, performed in both the geometries - in-plane as well as out of plane, revealed a lowest value of 1.19 (+/- 0.08) & times; 10-3 of alpha int in the film post-annealed at 773 K. In addition, the observed non-linear relation between the alpha int and the dynamical 'g'-factor suggests that the contribution of spin orbit interaction to the damping is far less compared to the damping contribution from the DOS present near the Fermi level. It is remarkable to note that the as-grown CFA films sputtered at room temperature exhibited a record lowest value of 1.73 (+/- 0.09) & times; 10-3 of alpha int. Attainment of such small value of Gilbert damping and having moderate magnetization in high spin polarized Co2FeAl Heusler films sputtered on the Si (100) substrate opens up their great application potential in future spintronics devices.
14.	Hrebynakha, V., et al. (författare) Influence of the external magnetic field on structural characteristics of granular Co-Cu thin film alloys 2024 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 606 Tidskriftsartikel (refereegranskat)abstract We present the results of experimental studies of the influence of an external magnetic field on the structural characteristics (surface roughness and structural entropy) of nanogranular thin-film system based on Co and Cu. The samples CoxCu100-x in a wide range of compositions (17 at. % ≤ x ≤ 69 at. %) with the thickness of d = 35 nm were obtained by electron-beam co-evaporation using two independent electron guns. After obtaining, the films were annealed in a vacuum at a temperature of 800 K for 30 min. The studies of magnetoresistive properties have shown that the maximum giant magnetoresistance (GMR) amplitude (1.7 % in the transverse and 1.6 % in the longitudinal measurement geometries) in a magnetic field of H = 4.5 kOe at room temperature was observed in the Co21Cu79 film alloy. Transmission electron microscopy showed that this sample contains hcp-Co granules with a size of L = 5 ÷ 12 nm in a matrix of metastable fcc-Cu(Co) solid solution. The influence of the external magnetic field on the structural characteristics and surface morphology of the Co21Cu79 thin-film alloy was investigated using atomic force microscopy (AFM). It was found that a first impact of application of external magnetic field with H = 0.5 kOe causes a decrease in the values of the arithmetic mean Ra, and quadratic mean Rq, of the film roughness and structural entropy S. A decreases in Ra by 8.5 %, Rq by 6.5 %, and structural entropy S by 6.5 % were observed. After application of a larger magnetic field with H = 1.0 kOe and during the subsequent relaxation of the structure within 15 h after the field is turned off, the values of the structural parameters of the film surface did not change significantly.
15.	Häggström, Lennart, et al. (författare) Mossbauer study of a ball-milled Co0.40Fe0.10Zr0.10B0.40 alloy 2022 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 560 Tidskriftsartikel (refereegranskat)abstract In this study, Fe-57 Mossbauer spectroscopy has been used to identify various Fe-restricted components formed in a ball-milled Co0.40Fe0.10Zr0.10B0.40 alloy for different milling times of 0 h, 8 h, 24 h, 72 h, 120 h, and 190 h. It is shown that the initial ball-milling results in formation of amorphous Fe1-xCox alloys. Further ball-milling introduces B into the neighborhood of the Fe atoms, and amorphous components with 3 and 4 B atoms as nearest-neighbors and next-nearest-neighbors are observed. Although the investigation about alloying of Fe and Zr is more difficult, it is concluded that there is no evidence of any crystalline FeZr phase. Furthermore, annealing the 190 h milled sample shows that crystalline Fe1-xCox alloys with very low x-values (x < 0.02) are formed.
16.	Kateb, Movaffaq, et al. (författare) Tailoring interface alloying and magnetic properties in (111) Permalloy/ Pt multilayers 2021 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 538 Tidskriftsartikel (refereegranskat)abstract We demonstrate preparation and characterization of permalloy Ni80Fe20 at.% (Py) multilayers in which the Py layers were deposited by two different sputter deposition methods. Namely, dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS), that represent low and moderate ionized flux fraction of the film forming material, respectively. We deposited ultrathin bilayers, i.e. 15 angstrom thick Py and 5 angstrom thick Pt, with 20 repetitions. Various effects such as substrate roughness, working gas pressure and sputter power are considered. The microstructure, texture and strain were characterized by X-ray diffraction, individual thicknesses and alloying were analysed by X-ray reflectivity, and uniaxial in-plane anisotropy probed by the magneto-optical Kerr effect. It is shown that HiPIMS deposition produces multilayers with reduced surface roughness regardless of the substrate surface roughness. Both dcMS and HiPIMS deposition present multilayers with strong (111) texture normal to the substrate. Using HiPIMS for deposition of the Py layer minimizes the alloying between individual layers compared to dcMS deposition performed at same average sputter power. However, this improvement in interface sharpness leads to a higher magnetic coercivity and a poor hard axis in the film plane. On the other hand, multilayers with alloying present a linear hard axis. Furthermore, we studied Py/Cu and Py/CuPt multilayers, prepared under identical conditions using HiPIMS. The results indicate that in the Py/Pt case, deterioration of the in-plane uniaxial anisotropy, is caused by inverse magnetostriction originating from the large lattice mismatch between Py and Pt. The Py/Pt multilayers that exhibit alloying have a less strained interface and have a well defined uniaxial anisotropy.
17.	Kibbou, M., et al. (författare) The electronic, magnetic and electrical properties of Mn2FeReO6 : Ab-initio calculations and Monte-Carlo simulation 2020 Ingår i: Journal of Magnetism and Magnetic Materials. - : ELSEVIER. - 0304-8853 .- 1873-4766. ; 495 Tidskriftsartikel (refereegranskat)abstract In this paper, a theoretical study of the electronic, magnetic and electrical properties of double perovskite Mn2FeReO6 with a high Curie temperature so far in magnetic oxides was conducted, using several methods such as Ab-initio and Statistical Physics like Monte-Carlo Simulations (MCS). However, the first principles calculations showed a half-metallic behavior from the density of states and band structures calculation, using PBE + U (apply on the elements Mn, Fe, and Re respectively). The critical temperature obtained by MCS has a great similarity with the experimental results.
18.	Kotnana, Ganesh, et al. (författare) Novel mixed precursor approach to prepare multiferroic nanocomposites with enhanced interfacial coupling 2020 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 511 Tidskriftsartikel (refereegranskat)abstract In the present work, we report the preparation of multiferroic PbZr0.52Ti0.48O3 (PZT)/CoFe2O4 (CFO) nanocomposites using a new synthesis technique that can maximize the surface area of contact, and hence, the interfacial coupling between the ferroelectric (PZT) and ferrimagnetic (CFO) phases. The samples have been characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM), and the physical (magnetic and dielectric) properties have been investigated. XRD confirms the presence of the desired PZT and CFO phases in the samples without any undesired secondary phases. We also observe a reduction in the particle size of CFO in the nanocomposites as evidenced by a line broadening of the XRD reflections corresponding to the pure CFO phase. The nanocomposites show hysteresis loops and ferrimagnetic-like behaviors in their M vs H curves at room temperature, even for samples with very low fraction of the CFO phase. The coercivity of the nanocomposites is marginally larger compared to that of pure CFO, which can be due to the change in magnetic anisotropy of the CFO phase due to its reduced particle size in the nanocomposites. Room temperature polarization versus electric field measurements show a significant increase in the coercive field after the incorporation of CFO inside the PZT matrix. This work illustrates a simple, cost-effective synthesis technique that can be used to prepare nanocomposites of functional materials with desired room temperature functionalities and enhanced interfacial coupling between the two phases.
19.	Lahraichi, Hanane, et al. (författare) Design of 2D half-metallic CoAl2S4 with robust ferromagnetism and high Curie temperature 2024 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 599 Tidskriftsartikel (refereegranskat)abstract Two-dimensional 2D ferromagnetic materials featuring intrinsic half-metallicity (HM) and high critical temperature Tc emerge as promising candidates for innovative low-dimensional spintronic devices. In this study, we employ first-principles calculations to predict a novel 2D half-metallic ferromagnet CoAl2S4 monolayer, a member of the layered AB2X4 family. The material’s energetic, mechanical, and dynamical stability is affirmed through analyses of its cohesive energy, elastic constants, and phonon spectrum, respectively. The ferromagnetic behavior observed in CoAl2S4 can be explained by the superexchange interaction of Co-S-Co bonds, consistent with the Goodenough–Kanamori rules. Notably, CoAl2S4 displays robust ferromagnetism with a Curie temperature reaching up to 435 K. The band structures show a large half-metal gap (2.83eV), ensuring the stability of the half-metallic state. Additionally, the CoAl2S4 monolayer demonstrates a preferential easy magnetization along the out-of-plane direction. Consequently, the rich CoAl2S4 monolayer is expected to boost advancements in spintronics, magnetostrictive materials, and magnetic memory devices.
20.	Lyaschenko, Sergey, et al. (författare) Optical and magneto-optical properties of epitaxial Mn2GaC MAX phase thin film 2021 Ingår i: Journal of Magnetism and Magnetic Materials. - : ELSEVIER. - 0304-8853 .- 1873-4766. ; 528 Tidskriftsartikel (refereegranskat)abstract We report measurements of the dielectric permittivity, optical conductivity and magnetic circular dichroism (MCD) of the epitaxial Mn2GaC MAX-phase thin film in an external magnetic field of up to 200 mT, at temperatures of 296 and 140 K and 1.4 to 3.5 eV. The optical conductivity and MCD spectra show absorption peaks which are consistent with the interband electronic transitions for different positions of Mn, Ga, and C ions as confirmed by theoretical calculations of the spin-dependent density of electronic states. The well-known structural phase transition at 214 K is also seen in the changes of optical, magneto-optical and surface magnetic properties of Mn2GaC in our experiment.
21.	Löfstrand, Julia, et al. (författare) Tuning in-plane magnetic anisotropy and temperature stability in amorphous trilayers 2023 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 586 Tidskriftsartikel (refereegranskat)abstract Better understanding of the nature of magnetic coupling in soft/hard nanocomposites paves the way for tailored exchange-spring magnets. We have investigated a series of amorphous magnetic thin films and trilayers of magnetically soft Co85(Al70Zr30)15 and magnetically hard Sm12Co81Ti7, produced with DC magnetron sputtering. The overall magnetic properties of the trilayers were investigated with focus on the effects of layer configuration and thicknesses on coercivity, originating from the Sm12Co81Ti7 phase, and uniaxial in-plane anisotropy induced from the Co85(Al70Zr30)15 phase. In addition, we found that the thermal stability of a 20 nm Sm12Co81Ti7 layer was significantly increased if surrounded by two 10 nm Co85(Al70Zr30)15 layers in a trilayer structure.
22.	Magnuson, Martin, 1965-, et al. (författare) Magnetic anisotropy in Cr2GeC investigated by X-ray magnetic circular dichroism and ab initio calculations 2020 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 501 Tidskriftsartikel (refereegranskat)abstract The magnetism in the inherently nanolaminated ternary MAX-phase Cr2GeC is investigated by element-selective, polarization and temperature-dependent, soft X-ray absorption spectroscopy and X-ray magnetic circular dichroism. The measurements indicate an antiferro-magnetic Cr-Cr coupling along the c-axis of the hexagonal structure modulated by a ferromagnetic ordering in the nanolaminated ab-basal planes. The weak chromium magnetic moments are an order of magnitude stronger in the nanolaminated planes than along the vertical axis. Theoretically, a small but notable, non-spin-collinear component explains the existence of a non-perfect spin compensation along the c-axis. As shown in this work, this spin distortion generates an overall residual spin moment inside the unit cell resembling that of a ferri-magnet. Due to the different competing magnetic interactions, electron correlations and temperature effects both need to be considered to achieve a correct theoretical description of the Cr2GeC magnetic properties.
23.	Makino, Hitoshi, et al. (författare) A study on the relationship of magnetic moments orientation in L10FePt network nanostructured film by electron energy-loss magnetic chiral dichroism using semi-core excitation spectra 2022 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 558 Tidskriftsartikel (refereegranskat)abstract In this study, we applied electron energy-loss magnetic chiral dichmism (EMCD), an electron counterpart of X-ray magnetic circular dichmism (XMCD), to a network nanostructured FePt L1(0) ordered alloy film to examine the relative orientation of magnetic moments between neighboring Fe and Pt atoms using the Fe-M-2,M-3, Pt-O-2,O-3, and Pt-N-6,N-7 semi-core excitation spectra with transmission electron microscopy and electron energy-loss spectroscopy. EMCD signals were successfully extracted from a large number of spectra using a dedicated data analysis procedure to obtain sufficient noise statistics. Results showed that the relative sign relation of the EMCD signals between the Fe and Pt absorption edges was consistent with that of the theoretical dielectric tensor while assuming that parallel magnetic moments exist between neighboring Fe and Pt. We believe the results of this study can be applied to alloys with different nanostructures to determine whether the spin configuration depends on the size and geometry of the nanostructures.
24.	Mallik, Sameer Kumar, et al. (författare) Transition metal substituted MoS2/WS2 van der Waals heterostructure for realization of dilute magnetic semiconductors 2022 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 560 Tidskriftsartikel (refereegranskat)abstract Atomically thin doped two dimensional (2D) layered materials manifest excellent magnetic features beneficial to the potential applications in spintronics. With the implementation of extensive first principles calculations, we demonstrate the MS2 (M = Mo, W) monolayers, as well as their van der Waals (vdW) hetero-bilayers as promising candidates for the successful realization of 2D dilute magnetic semiconductors with the incorporation of Mn and Co dopants. Under various pairwise doping configurations at different host atom sites, we report the electronic properties modifications induced change in magnetic exchange interactions. The magnetic coupling among the dopant pairs can be tuned between FM and AFM orderings via suitable doping adjustments. The developed interlayer exchange coupling between the vdW layers leads to strong and long-ranged ferromagnetic interactions which unleash robust magnetic moments with stable doping configurations. Our findings address the novel magnetic behavior of the layered vdW heterostructures and may further guide the future experimental efforts for the possible applications in modern electronics and nanoscale magnetic storage devices.
25.	Maltoni, piema929, et al. (författare) Exploring the magnetic properties and magnetic coupling in SrFe12O19/ Co1-XZnXFe2O4 & nbsp;nanocomposites 2021 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 535 Tidskriftsartikel (refereegranskat)abstract Among hard/soft nanocomposites (NCs), ferrite-based materials are potentially promising for developing exchange-coupled systems, thus leading to enhanced magnetic properties. In this regard, we investigate the role of the synthesis approach in the development of SrFe12O19/CoFe2O4 (SFO/CFO) NCs, with special focus on tuning the magnetic features of the softer phase (CFO) by introducing Zn2+ in the spinel structure. X-ray powder diffraction (XRPD), transmission electron microscopy (TEM) and squid magnetometry were employed to clarify the relationship between morphology, size, and magnetic properties of the NCs, pointing out the feasibility of this method in obtaining successfully exchange-coupled systems. This work shows how optimizing the intrinsic magnetic properties of the CFO may be used to tune the extrinsic ones of the NCs. Despite the promising results in magnetic coupling, our study clearly confirms/strengthens that an enhancement of remanent magnetization is the most important factor for improving the magnetic performance.
26.	Masood, A., et al. (författare) High-frequency power loss mechanisms in ultra-thin amorphous ribbons 2021 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier B.V.. - 0304-8853 .- 1873-4766. ; 519 Tidskriftsartikel (refereegranskat)abstract Soft magnetic amorphous materials with ultra-low power loss are highly desirable for high-frequency drive applications. The present work demonstrates the high-frequency power loss performance and underlying loss mechanisms in ultra-thin amorphous alloys. This is achieved by rapid-quenching amorphous alloys of Co-, CoFe- and Fe-rich systems, investigating their amorphous atomic structure, quantifying the saturation magnetostriction constants (λs), imaging magnetic domains at remanent magnetization, analyzing magnetization reversal from various magnetization levels, and finally, investigating the material loss performance over a broad frequency range (f = 50 kHz–2 MHz) at various excitation levels (Bm = 25–100 mT). The ultra-high performance of ultra-thin Co-rich amorphous ribbons, as compared to CoFe- and Fe-rich alloys, was attributed to the significantly low eddy current loss, due to the reduced thickness, and a minimal amount of excess loss, owning to minimal magnetoelastic contributions and magnetization reversal by rotation. The underlying loss mechanisms were analyzed by decomposing material loss into primary components and identifying the magnetization reversal mechanisms using minor hysteresis loops. In the Co-rich amorphous alloys, we suggest that magnetization reversal by rotation dominates, at least at low excitations, while in CoFe- and Fe-rich alloys domain wall displacement prevails and contributes significantly to the excess loss up to the MHz frequency range. Magnetization reversal by rotation in Co-rich alloys could be attributed to the zero/near-zero λs, and eventually low residual stress, leading to a homogeneous magnetic domain structure, as compared to the inhomogeneous “fingerprint-like” complex domains in highly magnetostrictive CoFe-rich alloys.
27.	Masood, Ansar, et al. (författare) On the correlation between glass forming ability (GFA) and soft magnetism of Ni-substituted Fe-based metallic glassy alloys 2020 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 504 Tidskriftsartikel (refereegranskat)abstract The present work aims to investigate the mechanism of glass formation and correlates it to the soft magnetism of Ni-substituted Fe-B-Nb alloys. The impact of ferrous Ni on the mechanism of glass formation and soft magnetism of Fe-based bulk metallic glasses was critically analyzed. By quantifying glass forming ability and soft magnetic characteristic for varying degrees of substitution, we observe a maximum in glass forming ability together with a minimum coercivity, which we suggest is due to an increased atomic packing density of the glassy phase. Interestingly, a monotonic increase of Curie temperature with increasing substitution of Ni was observed, which could be attributed to a reduction of an antiferromagnetic Fe-Fe interaction in the glassy iron-rich matrix. The overarching goal of this study is to explore the underlying mechanisms of enhanced glass forming ability, improved soft magnetic properties, and increased Tc of Ni-substituted Fe-based glassy alloys.
28.	Mondal, Ritwik, et al. (författare) Inertial effects in ultrafast spin dynamics 2023 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 579 Forskningsöversikt (refereegranskat)abstract The dynamics of magnetic moments consists of a precession around the magnetic field direction and a relaxation towards the field to minimize the energy. While the magnetic moment and the angular momentum are conventionally assumed to be parallel to each other, at ultrafast time scales their directions become separated due to inertial effects. The inertial dynamics gives rise to additional high-frequency modes in the excitation spectrum of magnetic materials. Here, we review the recent theoretical and experimental advances in this emerging topic and discuss the open challenges and opportunities in the detection and the potential applications of inertial spin dynamics.
29.	Muscas, Giuseppe, et al. (författare) Mesoscale magnetic rings : Complex magnetization reversal uncovered by FORC 2020 Ingår i: Journal of Magnetism and Magnetic Materials. - : ELSEVIER. - 0304-8853 .- 1873-4766. ; 502 Tidskriftsartikel (refereegranskat)abstract In this work, we investigate mesoscopic amorphous magnetic rings prepared by ion-implantation. The analysis is carried out combining conventional magnetization vs field measurements alongside MOKE microscopy imaging and, for the first time, first-order reversal curves (FORCs). With the information extracted from the FORC diagram, we can identify the presence of typical onion and vortex magnetic configurations, and also determine with high resolution the fields connected to their formation, stability, and annihilation. Furthermore, depending on the field and history, two different onion configurations exist, characterized by the presence of transverse or vortex domain walls. The FORC data reveal the different reversible/irreversible nature of the annihilation of the two onion configurations, and a signal peculiar of the presence of vortex domain walls. All these crucial information are not accessible with conventional M(H) loops, demonstrating that FORCs offer a unique perspective for the investigation of the physical phenomena of magnetic elements with complex geometries.
30.	Podmiljšak, Benjamin, et al. (författare) Additive-manufactured anisotropic magnets for harsh environments 2023 Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853. ; 586 Tidskriftsartikel (refereegranskat)abstract We describe the fabrication of SrFe12O19-based filaments, using polyphenylene sulphide (PPS) as the binder for the magnetic particles, and the subsequent printing of this filament with a 3D printer. PPS is an ideal polymer for applications in harsh environments, making it applicable for the automotive industry, where it is widely used with injection moulding. However, 3D printing this polymer introduces a major challenge. Because PPS is more difficult to extrude than polyamide, the filling factor in this study was set to 70 wt. %, which is lower than when used in injection moulding (close to 90 wt. %). The filament with a diameter of 2.75 mm was printed into a disk-shaped magnet with a diameter of 10 mm and a height of 4 mm using a HAGE 3D printer that uses a belt system for the filament extrusion. The magnets were printed onto a glass surface and onto a bulk Nd-Fe-B permanent magnet with an external magnetic field, parallel to the printer’s z-axis. Printing in the presence of a magnetic field was found to increase the magnet’s remanent magnetization by 61%, compared to an isotropic print. Without an external magnetic field we achieved a remanence of 23.9 emu/g for the 70 wt.% filling fraction, while when printing in a magnetic field, the value of the remanence improved to 39.7 emu/g because of the improved magnetic texture.
31.	Rahmani, Neda, et al. (författare) Realizing ferromagnetic insulators in electron doped double perovskites Sr(2-x)AxMnVO(6); A = Sn, Bi 2021 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 519 Tidskriftsartikel (refereegranskat)abstract The structural, electronic and magnetic properties of electron doped Sr2-xAxMnVO6 (A = Sn, Bi) for x = 0.5, 1.0, 1.5, 2.0 were investigated using density functional theory (DFT) within generalized gradient approximation (GGA). Rocksalt and layered type orderings of B(B') cationic sites in Sn/Bi doped Sr2MnVO6 (SMVO) double perovskites were considered and it was found that the most stable ordering is a rocksalt type ordering in both Sn and Bi doped systems for all x concentrations. A structural phase transition from tetragonal to monoclinic and triclinic structures was observed for different doped compounds. Calculations demonstrated a half metal-insulator transition for Sr2-xAxMnVO6 with x 2.0 and x 0.5 upon Sn and Bi doping, respectively. Like the parent compound, ferromagnetic coupling between Mn and V was found to be the ground state for all doping concentrations of Sn and Bi. The magnetic moment of SMVO enhanced significantly due to doping. Calculated distortion parameters and bond angles indicated that the end members of each series, Sn2MnVO6 and Bi2MnVO6, undergo a significant octahedral tilting and distortion, which may result in a large value of electric polarization and hence, may be suggested as potential multiferroic materials.
32.	Reddy, Indukuru Ramesh, et al. (författare) Pressure-driven structural and spin-state transition in a Hofmann clathrate coordination polymer 2021 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 524 Tidskriftsartikel (refereegranskat)abstract Hofmann-type organometallic frameworks are well known for their porous crystal structure, exhibiting interesting electronic, optical, and magnetic properties, and are therefore considered as promising materials for various technological applications. Here, using density functional theory+U (DFT+U) calculations, we investigate the spin-state transition in a newly synthesized Hofmann clathrate, namely the Fe{OS(CH3)(2)}(2){Ag(CN)(2)}(2) complex, by applying hydrostatic pressure as an external perturbation. Our study reveals that under a relatively low isotropic hydrostatic pressure, the complex exhibits a reversible spin switching, whereas it undergoes a structural phase transition when the pressure is larger and anisotropic. The spin state of the Fe atom in the Hofmann clathrate complex transforms from high spin to intermediate spin state under anisotropic compression of the lattice parameters. The coordination polymer complex remains a magnetic semiconductor after the pressure-driven structural transformation.
33.	Sayed, F., et al. (författare) LaFeO3-CoFe2O4 bi-magnetic composite thin films prepared using an all-in-one synthesis technique 2020 Ingår i: Journal of Magnetism and Magnetic Materials. - : ELSEVIER. - 0304-8853 .- 1873-4766. ; 503 Tidskriftsartikel (refereegranskat)abstract Bi-phasic composite films are generally grown as multilayers that result in layer-by-layer morphology with each layer having a distinct chemical composition. In this work, we report an all-in-one chemical synthesis technique combined with spin-coating to prepare single-layer bi-magnetic LaFeO3 (LFO)-CoFe2O4 (CFO) composite thin films with both phases co-existing in the same layer. The films have been characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM), and the magnetic properties have been probed using dc magnetometry at room and low temperature. The unique synthesis technique followed ensures homogeneity of the two phases on the nanoscale with grain sizes similar to 10 nm for CFO and few tens of nm for LFO, as observed from TEM images. XRD confirms the presence of only the desired LFO and CFO phases in the films without any undesired secondary phases. Magnetic hysteresis loops reveal a coercivity of similar to 0.2 T at room temperature that increases by nearly one order of magnitude at T = 5 K. The all-in-one synthesis technique reported here can be used to prepare different bi-phasic composites in the form of single-layer two-dimensional films as well as zero-dimensional nanoparticles by a suitable modification of the precursors, solvents, and chelating agents.
34.	Shapouri, Samaneh, et al. (författare) Physical characterization of copper oxide nanowire fabricated via magnetic-field assisted thermal oxidation 2021 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 524 Tidskriftsartikel (refereegranskat)abstract Magnetic fields can alter the growth of nanomaterials and, in some cases, ultimately lead to room temperature ferromagnetism (RTF). One promising approach for the growth of nanomaterials is thermal oxidation with both academic and industrial relevance. In this study, we evaluate the growth of copper oxide (CuO) nanowires by thermal oxidation method in a furnace adapted with a static magnetic field (generated by neodymium magnets) upon a pure copper foil in which the direction of a vector perpendicular to the surface of the foil (the direction of nanowires growth) is parallel or antiparallel to the magnetic field direction. Technical analysis including XRD, FESEM and EDAX are performed to provide insight into the CuO nanowire microstructure. To this end, we have made use of statistical surface characteristics such as fractal, autocorrelation and texture aspect ratio analysis demonstrating a correlation between the aforementioned characteristics and the magnetic field orientation. Additionally, VSM studies show the emergence of room temperature ferromagnetism for CuO nanowires grown parallel and antiparallel to the magnetic field. We expect that our approach will open up a new angle on room temperature ferromagnetism for novel fundamental and applied studies.
35.	Singh, Suraj, et al. (författare) Magnetodynamic properties of dipole-coupled 1D magnonic crystals 2021 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 539 Tidskriftsartikel (refereegranskat)abstract Magnonic crystals are magnetic metamaterials, that provide a promising way to manipulate magnetodynamic properties by controlling the geometry of the patterned structures. Here, we study the magnetodynamic properties of 1D magnonic crystals consisting of parallel NiFe strips with different strip widths and separations. The strips couple via dipole-dipole interactions. As an alternative to experiments and/or micromagnetic simulations, we investigate the accuracy of a simple macrospin model. For the case of simple strips, a model with a single free parameter to account for an overestimation of the out of plane demagnetization of the magnonic lattice is described. By adjusting this parameter, a good fit with experimental as well as micromagnetic results is obtained. Moreover, the Gilbert damping is found independent of lattice constant however the inhomogeneous linewidth broadening found to increase with decreasing stripe separation.
36.	Ström, Petter, et al. (författare) Synthesis of ferromagnetic thin films and engineering of their magnetic properties by Fe ion implantation in polycrystalline Pd 2022 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 552 Tidskriftsartikel (refereegranskat)abstract Ferromagnetic thin films were synthesized by implantation of Fe ions with energies between 40 keV and 120 keV in 60 nm of polycrystalline Pd. The possibility to engineer magnetic properties in such films through the Fe concentration depth profile was demonstrated. In-plane magnetic moments were measured both while varying the sample temperature at constant applied magnetic field, and varying the applied field at constant temperature. All samples were explicitly shown to exhibit ferromagnetism at sufficiently low temperature, with threshold temperatures in the range from 35 K to 140 K. Saturation moments at 5 K were between 3.5 and 4.6 Bohr magnetons per implanted Fe atom for implantation fluences between 5 × 1015 and 2.3 × 1016 ions/cm2. Coercivities were between 1 and 3 mT. The samples included in the study were carefully characterized with Rutherford backscattering spectrometry, and selected samples with elastic recoil detection analysis and cross-sectional transmission electron microscopy, providing information on Fe concentration profiles, impurity fractions, structure as well as sample modification during implantation. A new model was proposed to calculate the scaling of the films’ magnetic moments with temperature from the Fe concentration profiles. The model qualitatively reproduced the data and quantitative differences were explained. It can thus be applied to predict the modification of the magnetic moment at a given temperature for a similar film when the implantation parameters are varied.
37.	Tombuloglu, Huseyin, et al. (författare) The size of iron oxide nanoparticles determines their translocation and effects on iron and mineral nutrition of pumpkin (Cucurbita maxima L.) 2022 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 564 Tidskriftsartikel (refereegranskat)abstract The ability of nanoparticles (NPs) to migrate in the plant body is an important issue to ensure that the NPs reach the desired tissue and to be able to select the most efficient NPs for agricultural applications. In this study, the size impact of four different iron oxide NPs (8-10, 18-20, 20-40, and 30-50 nm referred as NP10, NP20, NP30, and NP40, respectively) on their translocation in pumpkin was elucidated. To assess the root-to-shoot trans -location, phloem sap was examined under transmission electron microscope (TEM). In addition, vibrating sample magnetometer (VSM) and inductively coupled plasma optical emission spectrophotometry (ICP-OES) analyses of stem and leaf tissues were performed to confirm size-dependent translocation. TEM and VSM analyses verified root-to-stem translocation of all tested NPs. The NPs treatment significantly altered the abundances of Mn, Cu, K, P, Al, Mg, and Na in tissues. The iron (Fe) content was abundant in plants treated with NP30 and NP20, and the lowest in plants treated with NP10 and NP40. Together with, only NP30 was found to be significantly trans -located to the leaves, where it was 393 mg/kg in DW, about 2.3 times that of control. These findings pointed out the size-dependent translocation of NPs. It seems that biological barriers in the vascular bundle appear to restrict the migration, especially for NPs with an average size of 40 nm and above in pumpkins. These findings are important for selecting the most suitable size of iron oxide NPs for use in agricultural practices.
38.	Vlasko-Vlasov, V. K., et al. (författare) Magnetic circuit for Abrikosov vortices : Vortex motion in a periodic labyrinth of magnetic T and I-shaped elements under a superconducting film 2022 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 557 Tidskriftsartikel (refereegranskat)abstract We explore tailored labyrinth-like vortex motion in a niobium film placed on top of periodic arrays of T and I -shaped permalloy elements by imaging the vortex distribution in magnetic fields applied perpendicular to the superconducting layer under different in-plane polarizations of the TI structure. At low temperatures, we observe pronounced meandering of vortex motion around the TI elements. Remarkably, vortices can easily penetrate the sample along the TI columns even though the average vortex pinning in the patterned area is larger than in a bare niobium film. Accordingly, at temperatures close to the superconducting transition temperature, Tc, the voltage-current curves in the patterned area show an earlier departure from the zero-resistivity state at small currents, followed by slower growth with increasing current as compared to the un-patterned film. We present a model based on magnetostatic interactions between magnetic charges at the edges of the polarized TI-elements and single magnetic charges of induced vortices to account for this behavior. We expect that similar magnetic structures imposing labyrinth-like vortex motion could be used for collective entanglement of vortices envisioned in quantum circuit operations.
39.	Warnatz, Tobias, et al. (författare) The influence of diameter on the magnetic saturation in Fe 84 Cu 16 /MgO [001] multilayered islands 2020 Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 496 Tidskriftsartikel (refereegranskat)abstract The saturation field of circular islands, consisting of [Fe84Cu16/MgO]9Fe84Cu16 multilayers, increases with decreasing diameter of the islands. When the diameter of the islands is below 450 nm the field induced changes are dominated by a coherent rotation of the moment of the Fe84Cu16 layers. For diameters of 2 μm and larger, a signature of domain nucleation and evolution is observed. The changes in the saturation field with diameter of the islands are ascribed to the interplay between interlayer exchange coupling, stray field coupling at the edges and the crystalline anisotropy of the Fe84Cu16 layers.

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