| 1. |
- Tarnavich, V., et al.
(författare)
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Magnetic field induced chirality in Ho/Y multilayers with gradually decreasing anisotropy
- 2017
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Ingår i: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 96:1
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Tidskriftsartikel (refereegranskat)abstract
- Metal rare-earth magnetic/nonmagnetic Ho/Y superlattice structures possess a coherent spin helix propagating through many superlattice layer repetitions. An externalmagnetic field applied in the film plane induces a nonzero average chirality of the helices. It is shown that the direction of the applied in-plane field can modify the value and sign of the chirality parameter.. The dependence of. on the relative angle of applied field during the field`-cooling procedure has an oscillatory character and can be described by simple sinusoidal function with p periodicity. The experimental finding is discussed from the point of view of an interbalance between Zeeman energy, magnetocrystalline anisotropy, and induced uniaxial anisotropy.
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| 2. |
- Tarnavich, V. V., et al.
(författare)
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Field-induced chirality in the helix structure of Ho/Y multilayers
- 2014
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 89:5, s. 054406-
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Tidskriftsartikel (refereegranskat)abstract
- We study the net chirality in the spin helix structure of Ho/Y multilayers induced by an in-plane applied magnetic field. The lifting of degeneracy of the chiral symmetry was revealed by means of polarized neutron reflectometry. Three samples of different thicknesses of the Ho and Y layers were grown by molecular-beam epitaxy. The chiral states are degenerated upon zero field cooling below the critical temperature TN=115±3 K. The chirality parameter γ rises during the field cooling procedure in the field range from 0 to 1 T and saturates at a value of 0.12±0.01. The chirality appears stepwise below TN and depends weakly on temperature. The phenomenon is interpreted in terms of the Dzyaloshinskii-Moriya interaction appearing at the interface between the Ho and Y layers.
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| 3. |
- Ukleev, V, et al.
(författare)
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Coherent charge and magnetic ordering in Ho/Y superlattice revealed by element-selective x-ray scattering
- 2019
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Ingår i: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 100:13
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic rare-earth/nonmagnetic metal superlattices are well-known to display chiral spin helices in the rare-earth layers that propagate coherently across the nonmagnetic layers. However, the underlying mechanism that preserves the magnetic phase and chirality coherence across the nonmagnetic layers has remained elusive. In this paper, we use resonant and element-specific x-ray scattering to evidence directly the formation of two fundamentally different long-range modulations in a holmium/yttrium (Ho/Y) multilayer: the known Ho chiral spin helix with periodicity 25 angstrom and a newly observed charge density wave with periodicity 16 angstrom that propagates through both the Ho and nonmagnetic Y layer. With x-ray circular magnetic dichroism measurements ruling out the existence of a magnetic proximity effect induced moment in the nonmagnetic Y layers, we propose that the charge density wave is also chiral, thus providing the means for the transmittance of magnetic chirality coherence between Ho layers.
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| 4. |
- Ciuciulkaite, Agne, MSc, 1991-, et al.
(författare)
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Magnetic and all-optical switching properties of amorphous TbxCo100-x alloys
- 2020
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Ingår i: Physical Review Materials. - : American Physical Society (APS). - 2475-9953. ; 4:10
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Tidskriftsartikel (refereegranskat)abstract
- Amorphous TbxCo100-x magnetic alloys exhibit a list of intriguing properties, such as perpendicular magnetic anisotropy, high magneto-optical activity, and magnetization switching using ultrashort optical pulses. Varying the Tb:Co ratio in these alloys allows for tuning properties such as the saturation magnetic moment, coercive field, and the performance of light-induced magnetization switching. In this paper, we investigate the magnetic, optical, and magneto-optical properties of various TbxCo100-x thin-film alloy compositions. We report on the effect the choice of different seeding layers has on the structural and magnetic properties of TbxCo100-x layers. We also demonstrate that for a range of alloys, deposited on fused silica substrates, with Tb content of 24-30 at. %, helicity-dependent all-optical switching of magnetization can be achieved, albeit in a multishot framework. We explain this property to arise from the helicity-dependent laser-induced magnetization on the Co sublattice due to the inverse Faraday effect. Our paper provides an insight into material aspects for future potential hybrid magnetoplasmonic TbCo-based architectures.
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| 5. |
- Hellsing, Maja S., et al.
(författare)
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Crystalline order of polymer nanoparticles over large areas at solid/liquid interfaces
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 100:22, s. 221601-
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Tidskriftsartikel (refereegranskat)abstract
- We report on the formation of large two-dimensional domains (about 20 cm2) of oriented and ordered structures of polystyrene particles dispersed in water at a solid/liquid interface. Gentle flow of the dispersed sample into the holder at a shear strain rate of about 0.1 s−1 caused particles at the air/latex meniscus to self-assemble in a regular structure on both solid silica or alumina surfaces. Scattering experiments show that the particle separation at the surface was the same as in the bulk and determined by repulsion arising from the charges on the particles. Close-packed planes formed parallel to the interface.
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| 6. |
- Jishiashvili, D., et al.
(författare)
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Germanium Nitride Nanowires Produced by Thermal Annealing in Hydrazine Vapor
- 2009
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Ingår i: Advanced Science Letters. - : American Scientific Publishers. - 1936-6612 .- 1936-7317. ; 2:1, s. 40-44
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Tidskriftsartikel (refereegranskat)abstract
- A simple pyrolytic: technology was developed in this paper for producing Germanium nitride nanowires. Hydrazine was used as the nitriding agent, while the 3 mol.% of water diluted in it served for producing volatile GeO molecules and for the accomplishment of mass transfer. The Ge3N4 nuclei appeared on the surfaces of GeOx clusters, formed after redeposition of GeO molecules. The growth of two types of nanowires was observed. The ball-shaped Ge tip surrounded with the amorphous GeO2 sheath served as a catalyst during the vapor-liquid-solid growth of tapered nanowires. Straight nanowires were produced through the oxide-assisted method. Tentative results on the blue-green photoluminescence of nanowires were obtained.
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| 7. |
- Kapaklis, Vassilios, et al.
(författare)
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Thermal fluctuations in artificial spin ice
- 2014
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Ingår i: Nature Nanotechnology. - 1748-3387 .- 1748-3395. ; 9:7, s. 514-519
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Tidskriftsartikel (refereegranskat)abstract
- Artificial spin ice systems have been proposed as a playground for the study of monopole-like magnetic excitations(1,2), similar to those observed in pyrochlore spin ice materials(3). Currents of magnetic monopole excitations have been observed's, demonstrating the possibility for the realization of magnetic-charge-based circuitry. Artificial spin ice systems that support thermal fluctuations can serve as an ideal setting for observing dynamical effects such as monopole propagation and as a potential medium for magnetricity investigations(1,2). Here, we report on the transition from a frozen to a dynamic state in artificial spin ice with a square lattice. Magnetic imaging is used to determine the magnetic state of the islands in thermal equilibrium. The temperature-induced onset of magnetic fluctuations and excitation populations are shown to depend on the lattice spacing and related interaction strength between islands. The excitations are described by Boltzmann distributions with their factors in the frozen state relating to the blocking temperatures of the array. Our results provide insight into the design of thermal artificial spin ice arrays where the magnetic charge density and response to external fields can be studied in thermal equilibrium.
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| 8. |
- Maccaferri, Nicolò, Dr. 1988-, et al.
(författare)
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Nanoscale magnetophotonics
- 2020
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 127:8
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Tidskriftsartikel (refereegranskat)abstract
- This Perspective surveys the state-of-the-art and future prospects of science and technology employing nanoconfined light (nanophotonics and nanoplasmonics) in combination with magnetism. We denote this field broadly as nanoscale magnetophotonics. We include a general introduction to the field and describe the emerging magneto-optical effects in magnetoplasmonic and magnetophotonic nanostructures supporting localized and propagating plasmons. Special attention is given to magnetoplasmonic crystals with transverse magnetization and the associated nanophotonic non-reciprocal effects and to magneto-optical effects in periodic arrays of nanostructures. We also give an overview of the applications of these systems in biological and chemical sensing, as well as in light polarization and phase control. We further review the area of nonlinear magnetophotonics, the semiconductor spin-plasmonics, and the general principles and applications of opto-magnetism and nano-optical ultrafast control of magnetism and spintronics. © 2020 Author(s).
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| 9. |
- Mishra, K., et al.
(författare)
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Ultrafast Demagnetization Control in Magnetophotonic Surface Crystals
- 2022
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 22:23, s. 9773-80
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic memory combining plasmonics and magnetism is poised to dramatically increase the bit density and energy efficiency of light-assisted ultrafast magnetic storage, thanks to nanoplasmon-driven enhancement and confinement of light. Here we devise a new path for that, simultaneously enabling light driven bit downscaling, reduction of the required energy for magnetic memory writing, and a subtle control over the degree of demagnetization in a magnetophotonic surface crystal. It features a regular array of truncated-nanocone-shaped Au-TbCo antennas showing both localized plasmon and surface lattice resonance modes. The ultrafast magnetization dynamics of the nanoantennas show a 3-fold resonant enhancement of the demagnetization efficiency. The degree of demagnetization is further tuned by activating surface lattice modes. This reveals a platform where ultrafast demagnetization is localized at the nanoscale and its extent can be controlled at will, rendering it multistate and potentially opening up so-far-unforeseen nanomagnetic neuromorphic-like systems operating at femtosecond time scales controlled by light.
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| 10. |
- Moubah, Reda, et al.
(författare)
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Discrete Layer-by-Layer Magnetic Switching in Fe/MgO(001) Superlattices
- 2016
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Ingår i: Physical Review Applied. - : American physical society. - 2331-7019. ; 5:4
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Tidskriftsartikel (refereegranskat)abstract
- We report on a discrete layer-by-layer magnetic switching in Fe/MgO superlattices driven by an antiferromagnetic interlayer exchange coupling. The strong interlayer coupling is mediated by tunneling through MgO layers with thicknesses up to at least 1.8 nm, and the coupling strength varies with MgO thickness. Furthermore, the competition between the interlayer coupling and magnetocrystalline anisotropy stabilizes both 90 degrees and 180 degrees periodic alignment of adjacent layers throughout the entire superlattice. The tunable layer-by-layer switching, coupled with the giant tunneling magnetoresistance of Fe/MgO/Fe junctions, is an appealing combination for three-dimensional spintronic memories and logic devices.
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