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Sökning: L773:0304 8853 > (2000-2004)

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1.
  • Hanson, Maj, 1939, et al. (författare)
  • Magnetic properties of epitaxial Ni(001) films and sub-micron particles
  • 2001
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 236, s. 139-50
  • Tidskriftsartikel (refereegranskat)abstract
    • The magnetic properties of Ni particles with well-defined geometry, prepared by electron lithography from epitaxial Ni(001) films of thickness 50 and 60 nm were studied. The particles were circles with diameters 0.6 m and rectangles with sides 0.9 m and 0.3 m, that were positioned in square and rectangular lattices, having lattice constants about twice the particle dimensions. Reference samples and particles with the lattices oriented along the [100] and [110] directions were prepared. Hysteresis curves were obtained for particles and reference samples, in the field range 2T at temperatures between 50 and 300 K. The particles were further imaged by magnetic force microscopy. The coercivities of the particles are about the same as that of the reference samples, being of the order of 10 mT at room temperature and increasing with decreasing temperature. This may be explained by the temperature dependence of the magnetic anisotropy of the Ni film, estimated to K1=-12.5, -12.8 and -87.6 kJ m-3 at 295, 250 and 50 K, respectively. Whereas the hysteresis curves of the particles are governed by the intrinsic properties of the starting film in low fields, the decreased lateral size influences the behaviour in higher fields as demagnetization effects and features characteristic for annihilation and nucleation of domain walls. One of the samples, rectangles with the long axis alone the [110] direction, has a significantly higher remanence and coercivity than the others. The magnetic images show that the demagnetized state of this sample comprises both single-domain and multidomain particles. Corresponding images showed only multidomain particles in all other samples. Thus it was concluded that the actual size (0.9 m0.3 m50 nm) is close to the critical size for single domains in Ni
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2.
  • Uriarte, J L, et al. (författare)
  • Properties of FeNiB-based metallic glasses with primary BCC and FCC crystallisation products.
  • 2003
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853. ; 254-255, s. 532-534
  • Tidskriftsartikel (refereegranskat)abstract
    • FeSiB tapes have long been commercialised for their excellent soft-magnetic properties but do not manifest a glass transition temperature Tg as crystallisation intervenes. In this work, we present the crystallisation and properties of two Fe-based glasses, which show a glass transition before crystallisation. Using Ni and Co substitution, we can design glasses that form primary FCC or BCC FeNiCo solutions in their first stage of crystallisation followed by the formation of the metastable (FeNiCo)4B (C6Cr23-type cF116) intermetallic phase. Thermal and structural and magnetic properties were compared during heat treatment.
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3.
  • Adachi, N., et al. (författare)
  • Magnetic properties of single crystal film Bi3Fe5O12 prepared onto Sm3(Sc, Ga)5O12(111)
  • 2002
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 242:Part 2, s. 775-777
  • Tidskriftsartikel (refereegranskat)abstract
    • Magnetic properties of single crystal Bi3Fe5O12 has been investigated in the temperature range between 2 and 670K. The Sm3(Sc,Ga)5O12 wafer has been used for substrates. Due to the small contribution of the substrate's magnetization, the film's magnetization can be clearly estimated to be 2040G (0K) and the Curie temperature has been estimated to be around 650K.
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4.
  • Andersson, P. H., et al. (författare)
  • The effect of hydrogenation on the crystal structure and magnetic state in Pd3Mn
  • 2001
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 226-230:Part 1, s. 1040-1041
  • Tidskriftsartikel (refereegranskat)abstract
    • The effect of hydrogenation on the crystalstructure and magneticstate of Pd3Mn has been calculated using a full-potential linear augmented plane wave method in the local spin density approximation.When hydrogenated the system is observed to transform from the tetragonal Al3Zr structure to the cubic Cu3Au structure. When hydrogen is removed the system remains in a meta-stable cubic phase for an extended period of time. The structural transformations are associated with a change in the magneticstate. Our theoretical results of magnetic as well as crystalstructure stability are in agreement with experiments, especially the destabilization of the tetragonal structure for increased hydrogen concentration and complex magneticstructure of the cubic phases. The latter is analyzed in terms of Fermi surface nesting.
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5.
  • Batlle, X., et al. (författare)
  • The oxidation state at tunnel junction interfaces
  • 2003
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 260:02-jan, s. 78-83
  • Tidskriftsartikel (refereegranskat)abstract
    • The oxidation state at the interfaces of Nb/Al-AlOx/Pb junctions is discussed. Conductance-voltage curves below and above the superconducting temperature suggest tunneling conduction, while X-ray photoelectron spectroscopy shows the existence of a thin AlOx layer at the Nb/Al interface. We demonstrate that at the usual 10(-7) Torr range of base pressures in the sputtering chamber, this is due to the time elapsed between the deposition of the Nb and Al bottom layers, in both Nb/Al-AlOx/Pb tunnel junctions and Nb/Al bilayers. We also give some direct evidence of the oxidation of the top Pb electrode on the Nb electrode surface. Such oxidation probably occurs at the pinholes of the intermediate Al-AlOx layer of the tunnel junctions, as a consequence of the oxidation state at the Nb/Al interface, which helps to avoid barrier shorts and enhances the quality of the tunnel barrier. We therefore suggest that there is oxide formation in other places besides where there is an actual oxide deposited. This is relevant for the performance of magnetic tunnel junctions since in most tunneling studies it is assumed that once the oxide is deposited, that is the only place where there is an oxide. This is also a very general statement applicable to thin film systems.
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6.
  • Colarieti-Tosti, M., et al. (författare)
  • Crystal field levels in lanthanide systems
  • 2001
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 226-230:Part 1, s. 1027-1028
  • Tidskriftsartikel (refereegranskat)abstract
    • Crystalfieldlevels in lanthanide compounds have been calculated by first-principles theory, combining the strength of the standard model for rare earths in treating the localized 4f electrons and the power of Density Functional Theory in describing the, weakly correlated, delocalized, electrons. The stability of our calculations has been checked against changes of the constraints in the Full Potential-LMTO implementation. The assumption of weak 4f–4f inter-atomic interactions has also been checked by means of supercell calculations. Suggestions for the treatment of magnetic systems on a similar basis are given.
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7.
  • Edmonds, K. W., et al. (författare)
  • Magnetism of exposed and Co-capped Fe nanoparticles
  • 2000
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 220:1, s. 25-30
  • Tidskriftsartikel (refereegranskat)abstract
    • The effect of capping a dilute assembly of nanoscale mass-selected Fe clusters with a Co thin film has been studied using X-ray magnetic circular dichroism (XMCD). The clusters, containing around 400 atoms, were deposited in situ from a gas-aggregation source onto highly oriented pyrolytic graphite. The exposed clusters possess magnetic moments that are enhanced compared to the bulk, by around 4% for m(spin) and around 75% for m(orb). In addition, a surface core level shifted component is observed in the L-3.2 XMCD spectrum. Upon adding the Co layer, the surface component disappears, m(orb) is decreased for the Fe clusters, and m(spin) increases. The exposed clusters are magnetically isotropic but a strong in-plans anisotropy is observed after depositing the Co overlayer. We attribute this to the shape of the Co islands in which the Fe clusters are embedded.
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8.
  • Edmonds, K. W., et al. (författare)
  • Size dependence of the magnetic moments of exposed nanoscale iron particles
  • 2001
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 231:1, s. 113-119
  • Tidskriftsartikel (refereegranskat)abstract
    • The magnetic moments in exposed, mass-selected, nanoscale Fe clusters in the size range 1.89-2.20 nm (300-475 atoms), deposited onto graphic in situ have been measured by X-ray magnetic circular dichroism. The smallest clusters possess moments that are enhanced by around 4% for m(spin) and 80% for m(orb) and decrease towards the bulk value with increasing size. The larger clusters show an in-plane anisotropy that is consistent with the anisotropy in the orbital moment. The smallest clusters are, within experimental error, magnetically isotropic. The anisotropy constant in the 475-atom clusters is significantly higher than the bulk value.
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9.
  • Engdahl, Göran, et al. (författare)
  • The feasibility to model a 3-leg core type medium frequency power transformer by use of a dual Cauer circuit
  • 2002
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 242, s. 1210-1213
  • Tidskriftsartikel (refereegranskat)abstract
    • A model for medium frequency power transformers is suggested, The model is able to treat arbitrary topologies by use of Cauer circuits for core and windings. An implementation example is given for a 1-phase transformer with turn ratio 1:1. The model can be extended to include winding insulation materials by use of lumped capacitive and resistive circuit elements.
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10.
  • G.E. Grechnev,, et al. (författare)
  • Electronic structure and magnetic properties of Lithium manganese spinels
  • 2003
  • Ingår i: J.Magn. Magn. Matt.. ; 258, s. 287-289
  • Tidskriftsartikel (refereegranskat)abstract
    • Electronic and magnetic structures of the spinel-type lithium–manganese oxides LixMn2O4, x=0,0.5,1, are studied ab initio by employing a full-potential LMTO method. The effect of the orthorhombic distortion on electronic structure and magnetism of LiMn2O4 was investigated, and our calculations do not show a substantial charge ordering at the structural transition from the cubic spinel to the orthorhombic structure.
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11.
  • Kim, D. K., et al. (författare)
  • Characterization and MRI study of surfactant-coated superparamagnetic nanoparticles administered into the rat brain
  • 2001
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 225:02-jan, s. 256-261
  • Tidskriftsartikel (refereegranskat)abstract
    • A pre-clinical study has been carried out for the utilization of magnetite (Fe-3 O-4) nanoparticles as a diagnostic tracer for MRI. Surfactant-coated Fe3O4 nanoparticles have been synthesized by a chemical coprecipitation method with a narrow particle size of around 6 nm. Preliminary experiments demonstrated the feasibility of using superparamagnetic Fe-3 O-4 nanoparticles as contrast agents in MR imaging.
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12.
  • Kim, D. K., et al. (författare)
  • Synthesis and characterization of surfactant-coated superparamagnetic monodispersed iron oxide nanoparticles
  • 2001
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 225:02-jan, s. 30-36
  • Tidskriftsartikel (refereegranskat)abstract
    • Synthesis and coating of superparamagnetic monodispersed iron oxide nanoparticles was carried out by chemical solution method. Controlled co-precipitation technique was used to prevent undesirable critical oxidation of Fe2+. The obtained Fe3O4 nanoparticles were coated with sodium oleate. Low-held AC susceptibility and SQUID measurement show superparamagnetism with a blocking temperature around 150K, and almost immeasurable remanence and coercivity.
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13.
  • Korenivski, Vladislav (författare)
  • GHz magnetic film inductors
  • 2000
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 215, s. 800-806
  • Tidskriftsartikel (refereegranskat)abstract
    • Use of magnetic films for miniaturization of planar inductors operating at ultra-high frequencies is reviewed. Materials and design aspects determining the efficiency of the devices are analyzed. Mechanisms involved in magnetic dissipation and their role in limiting the device operation frequency range and quality factor are discussed. Typical inductor geometries are considered. A magnetically sandwiched strip inductor is argued to hold a promise for GHz applications.
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14.
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15.
  • Mikhailova, M., et al. (författare)
  • Magnetic dilution of complex ferrates
  • 2002
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 242, s. 741-743
  • Tidskriftsartikel (refereegranskat)abstract
    • The magnetic and structural properties of La1+0.85yBa1-0.85yFeyAl1-yO4 (0.0056less than or equal toyless than or equal to0.088) solid solutions have been investigated to demonstrate the dependence of the valence state of iron atoms on the composition of sublattice. From the magnetic susceptibility measurements. the coexistence of Fe(II)-Fe(III) hetero valence states has been confirmed and the results showed the tendency of these atoms to form clusters.
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16.
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17.
  • PremKumar, R., et al. (författare)
  • Relative effect(s) of texture and grain size on magnetic properties in a low silicon non-grain oriented electrical steel
  • 2003
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 264:1, s. 75-85
  • Tidskriftsartikel (refereegranskat)abstract
    • Hot rolled low Si (silicon) non-grain oriented electrical steel was cold rolled to different reductions. Cold rolled material was subsequently recrystallized, 650°C and 2 h, and then temper rolled (to 7% reduction) for the final grain growth annealing and decarburization treatment at 850°C for 2–24 h. The development of texture, grainsizeandmagneticproperties were characterized at different stages of processing. Effect of textureonmagneticproperties (watt loss and permeability) was observed to be best represented by the ratio of volume fractions of (111)〈uvw〉/(001)〈uvw〉 fibers, as estimated by convoluting X-ray ODFs (orientation distribution functions) with respective model functions. Such a ratio was termed as generalized texture factor (tf) for the non-grain oriented electrical steel. An effort was made to delink effects of grainsizeandtexture, as represented by respective tf, on watt loss and permeability by careful analysis of experimental data. In general, low tf and/or high grainsize were responsible for low watt loss and high permeability. However, individual effect of grainsize or tf onmagneticproperties was less significant at low tf or large grainsize, respectively. An attempt was made to fit regression equations, namely—linear, exponential and power, relating magneticproperties with tf andgrainsize, limiting the fitting parameters to 3. Least standard deviations, between experimental and predicted values, were obtained by power regression equations for both magneticproperties.
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18.
  • Ström, Valter, et al. (författare)
  • A novel method for magnetic imaging : determination of local in-plane susceptibility at a surface
  • 2000
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 215, s. 723-725
  • Tidskriftsartikel (refereegranskat)abstract
    • Using a combined read/write head, a new instrument has been developed to determine the local in-plane magnetic susceptibility in magnitude and orientation at a micron length scale. Applications of this instrument to image the susceptibility distribution over ferromagnetic, as well as superconducting surfaces are presented. As far as we know, such microscopic magnetic information cannot be measured by other techniques.
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19.
  • Sukstanskii, A., et al. (författare)
  • Magnetostatic spin waves in metallic multilayers
  • 2000
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 218:03-feb, s. 144-150
  • Tidskriftsartikel (refereegranskat)abstract
    • Magnetostatic spin waves in a multilayer film consisting of two magnetic conductive layers separated by a nonmagnetic conductor are analyzed. Two magnetostatic spin wave branches are shown to exist and their dispesion laws are analyzed. Structures of finite width, which are relevant for device applications, are also considered.
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20.
  • Urech, Mattias, et al. (författare)
  • Magnetoresistance in Co/AlOx/Co tunnel junction arrays
  • 2002
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 249, s. 513-518
  • Tidskriftsartikel (refereegranskat)abstract
    • Lateral arrays of Co/AlOx/Co junctions with dimensions down to 60 nin and inter-junction separations similar to60-100 nm have been fabricated and analyzed for possible coherent tunneling effects. Extra attention is paid to avoid uncertainties due to inconsistencies in switching and/or resistance of successive barriers. We observe similar to10% magnetoresistance enhancement at moderate bias in double junctions that cannot be accounted for by a simple model of two resistsors in series.
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21.
  • Åkerman, Johan, et al. (författare)
  • Criteria for ferromagnetic-insulator-ferromagnetic tunneling
  • 2002
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 240:03-jan, s. 86-91
  • Tidskriftsartikel (refereegranskat)abstract
    • The Rowell criteria, commonly used to identify tunneling in magnetic tunnel junctions (MTJ), are scrutinized. While neither the exponential-thickness dependence of the conductivity nor fits of non-linear transport data are found to be reliable tunneling criteria, the temperature-dependent conductivity does remain a solid criterion. Based on experimental studies of the bias and temperature-dependent resistance and magnetoresistance of MTJs, with and without shorted barriers, a new set of criteria is formulated.
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22.
  • Abdu, Yassir, et al. (författare)
  • Coexisting antiferromagnetism and ferromagnetism in mechanically alloyed Fe-rich Fe-Ni alloys : Implications regarding the Fe-Ni phase diagram below 400 °C
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 280:2-3, s. 395-403
  • Tidskriftsartikel (refereegranskat)abstract
    • Fe–Ni alloys below the Invar region with compositions Fe100−xNix (x=21, 24, and 27 at%) were prepared by high-energy ball milling technique (mechanical alloying). The as-milled samples, characterized by X-ray diffraction and Mössbauer spectroscopy, contain a mixture of α (BCC) and γ (FCC) phases, whereas the samples annealed at 650°C for 0.5 h show a single γ (FCC) phase displaying a single line Mössbauer spectrum at room temperature (RT). At low temperature, the Mössbauer spectra of annealed Fe76Ni24 and Fe73Ni27 alloys show the existence of a magnetically split pattern together with a broad singlet, which are ascribed to a high-moment ferromagnetic Ni-rich phase and a low-moment Fe-rich phase, respectively. The Fe-rich phase in annealed Fe76Ni24 alloy, which is paramagnetic at RT, undergoes antiferromagnetic ordering at ∼40 K, estimated from the dramatic line broadening of its spectrum, giving rise to a small hyperfine field (e.g. ∼2 T at 6 K). The coexistence of these phases is attributed to phase segregation occurring in these alloys as a result of enhanced atomic diffusion. The stability of these alloys towards martensitic (FCC→BCC) transformation at low temperatures is discussed in connection with the Fe–Ni phase diagram below 400°C.
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23.
  • Abdu, Yassir, et al. (författare)
  • Field induced local magnetic moments in gamma-fcc Fe-Ni anti-Invar alloys
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 280, s. 243-250
  • Tidskriftsartikel (refereegranskat)abstract
    • Mössbauer spectroscopy in longitudinal external fields (up to 7 T) and SQUID magnetometry (up to 5 T)measurements have been carried out on mechanically alloyed (MA) g (FCC) Fe100xNix (x ¼ 21; 24, and 27 at%) alloysat room temperature. The zero-field M.ossbauer spectra of these alloys show only singlets. The high field M.ossbauerresults indicate that large amounts of the material is in the paramagnetic state, giving rise to two spectral componentswith their effective fields almost linearly depend on the external field, but with slopes that are smaller than unity. The infieldM.ossbauer spectra of the x ¼ 27 at% alloy show an additional component with a hyperfine field of E21 T, whichis attributed to Ni-rich (>30 at% Ni) clusters (domains) of ferromagnetically ordered HM phase that behavessuperparamagnetically at room temperature and shows a non-linear character in the magnetization (M–H) curves atlow fields. This HM phase is also present in the x ¼ 21 and 24 at% samples but with smaller amounts. The resultssuggest induced hyperfine fields and hence induced moments in the paramagnetic components, which increases withincreasing Ni contents. Taenite-enriched samples from the metal particles of two stony meteorites, Al Kidirate (H6)and New Halfa (L4), are also studied by high field M.ossbauer spectroscopy and the results are compared to that ofMA samples.
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24.
  • Austrin, L., et al. (författare)
  • A modeling approach of a magnetic amplifier
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 272, s. E1709-E1710
  • Tidskriftsartikel (refereegranskat)abstract
    • New soft magnetic materials made possible the use of the magnetic amplifier technology in designing competitive electric power supplies. This technology is used in the Swedish. fighter aircraft Gripen, being also attractive for future more electrical aircraft systems due to the possibility to achieve a compact and robust design. A modeling approach of a magnetic amplifier based on the magnetic hysteresis of the core material is presented here for a common amorphous magnetic alloy.
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25.
  • Björck, Matts, et al. (författare)
  • Element-specific magnetic moment profile in BCC Fe/Co superlattices
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 284, s. 273-280
  • Tidskriftsartikel (refereegranskat)abstract
    • BCC Fe/Co superlattices with individual layer thicknesses in the range of 2–9 monolayers have been investigated byX-ray magnetic circular dichroism in combination with SQUID magnetometry in order to study the magnetic momentdistribution in the superlattices. The magnetic moment for Co was found to remain constant, within 0:1 mB=atom, at1:6 mB=atom for all the superlattices. The Fe atoms at the interface have an enhanced moment of about 3:0 mB=atom. Inaddition, a complex dependence of the size of the moments on the thickness of the Fe layer was found and attributed tointerface roughness effects. Element-specific hysteresis curves were also recorded. These measurements show that themagnetic moments of Fe and Co were, as expected, coupled during reversal of the magnetic moment direction.
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26.
  • Chakhalian, Jacques, et al. (författare)
  • Impurity effects in quasi-one-dimensional S=1/2 antiferromagnetic chain KCuF3 studied by muon spin rotation
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; 272-276:Part 2, s. 979-980
  • Tidskriftsartikel (refereegranskat)abstract
    • The local magnetic susceptibility wloc around a positive muon in quasi-one-dimensional spin 1/2 antiferromagnetic chain compounds dichlorobis KCuF3 has been investigated using muon spin rotation/relaxation muSR: We compare chi_loc with the bulk magnetic susceptibility chi measured in a SQUID magnetometer. In all cases there is a dramatic difference between chi_loc and chi; as predicted by theory.
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27.
  • Edström, Kristina, et al. (författare)
  • The crystal and magnetic structure of nonstoichiometric K+ beta-ferrite
  • 2000
  • Ingår i: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. - 0304-8853. ; 212:3, s. 347-354
  • Tidskriftsartikel (refereegranskat)abstract
    • The crystal and magnetic structure of K+ beta-ferrite, K1.33Fe12O17, has been studied with neutron powder diffraction (lambda = 1.47) at 10, 295 and 923 K. Parameters describing the crystal and magnetic structure were refined with the Rietveld method. A m
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28.
  • Eggert, Sebastian, 1966, et al. (författare)
  • Magnetic order and moment distribution in doped spin-chain systems
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; 272-276:Suppl., s. E647-
  • Tidskriftsartikel (refereegranskat)abstract
    • We consider the effect of doping on the magnetic order in quasi one-dimensional (1D) antiferromagnets. First the detailed magnetic response of nite spin-1 2 chains in the presence of a staggered eld is determined, which by itself shows an interesting crossover as function of length and eld strength. We can then understand the ordering by including an effective coupling between the chains, which results in a N!eel-ordered phase at low temperatures, but with a broad distribution of magnetic moments that has to be determined self-consistently.
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29.
  • Eriksson, Therese, et al. (författare)
  • Crystal structure and magnetic properties of the new phase Mn3IrSi
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; :272-276, s. 823-825
  • Tidskriftsartikel (refereegranskat)abstract
    • A new phase in the ternary Ir–Mn–Si system has been synthesised. From powder neutron diffraction data the crystal structure was determined to be of the AlAu4 type and to be described in the cubic space group P213 with the unit cell a=6.4973(3) Å. Susceptibility measurements using a SQUID-magnetometer showed a transition typical of antiferromagnetism, with TN=210 K. Low temperature antiferromagnetic order is confirmed by extra peaks in neutron diffractograms recorded at 10 and 80 K.
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30.
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31.
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32.
  • Felton, S., et al. (författare)
  • Micromagnetic studies of Fe/Co ellipses with competing anisotropy contributions
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; 272-276:SUPPL. 1, s. e1297-
  • Tidskriftsartikel (refereegranskat)abstract
    • The effects of competing magneto-crystalline and shape anisotropies on magnetization reversal were studied in situ in arrays of sub-micron Fe/Co ellipses of compositions Fe2/Co6 and Fe8/Co3 with magnetic force microscopy (MFM). A simple model assigning magnetization values to the different types of domain structures observed in the MFM images was used to estimate the field dependence of the total magnetization of a sample. The agreement with macroscopic magnetization measurements is discussed.
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33.
  • Goll, G., et al. (författare)
  • conInvestigation of Sr2RuO4-Pt tacts in an applied magnetic field
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; 272:SUPPL. 1, s. E197-E198
  • Tidskriftsartikel (refereegranskat)abstract
    • We investigated the spin-triplet superconductor Sr 2 RuO 4 by means of conductance measurements of normal conductor/ superconductor point contacts. We present results that show a linear dependence of the excess current as a function of temperature and applied magnetic fields over a wide range of the phase diagram. Applying a magnetic field larger than the upper critical field B c2 suppresses completely the features related to superconductivity and a conductance minimum at V = 0 occurs which becomes more pronounced with increasing field and persists even above T c up to several K. © 2003 Elsevier B.V. All rights reserved.
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34.
  • Hanson, Maj, 1939, et al. (författare)
  • Influence of post-annealing on the properties of Fe50Pt50 film and submicron size particles
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; 272-276:SUPPL. 1, s. e1297-
  • Tidskriftsartikel (refereegranskat)abstract
    • The magnetic properties of a 48 nm thick Fe50Pt50 film and submicron size elements made of the film were investigated. The initial film was grown by DC magnetron sputtering and post-annealed during 30 min at 300°C. Arrays of circular dots with diameters d = 200, 300 and 550 nm and a reference sample (diameter 1.7mm) were made of the film by electron lithography and Ar ion milling. After structural analysis by X-ray diffraction (XRD) and characterization by magnetization measurements and magnetic force microscopy, all samples were further annealed during 30min at 600°C. The XRD scans show that this led to an improvement of the crystalline quality in all samples, to a degree depending on the size of the dots. Both the structural and magnetic measurements imply that after the second heat treatment all samples have the easy magnetocrystalline direction (c-axis) mainly in the plane of the film, while the initial structures were characterized by a random distribution of c-axes.
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35.
  • Hernandez, C., et al. (författare)
  • Magnetotransport properties of short period GaMnAs/InGaAs superlattices
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; 272, s. 1429-1430
  • Tidskriftsartikel (refereegranskat)abstract
    • Magnetotransport properties of GaMnAs/InGaAs superlattice structure and GaMnAs/GaAs single layers have been investigated from 4 to 300 K and magnetic fields up to 22.5 T. All these magnetic semiconductors show the so-called "paramagnetic-to-ferromagnetic phase transition''. However, in GaMnAs/InGaAs superlattice beside the Curie Wiess temperature (T-c similar to 40 K), a new phase transition is observed close to 13 K. (C) 2004 Elsevier B.V. All rights reserved.
  •  
36.
  • Holmström, Erik, et al. (författare)
  • Structural and magnetic aspects of multilayer interfaces
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 272-276, s. 941-
  • Tidskriftsartikel (refereegranskat)abstract
    • We show that it is possible to obtain quantitative information about the interface quality by considering the magnetic moments of Fe/V multilayers. We derive a parameter space describing the quality of interfaces and argue that most of the experimentally grown samples lie within a smaller segment of this space.
  •  
37.
  • Isaev, Eyvaz, et al. (författare)
  • Intrinsic defects and transition metal impurities in GaAs
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 272:3, s. 1961-1962
  • Tidskriftsartikel (refereegranskat)abstract
    • Thermodynamics of intrinsic point defects, 3d-transition metal (TM) impurities, and various defect pairs in GaAs have been studied by means of the locally self-consistent Green's function method. Antisite defects, As-Ga, are found to be the most energetically favorable defects in the As-rich GaAs. The studied TM impurities (V, Cr, Mn, and Fe) are found to form substitutional alloys on the Ga sublattice. The magnetic moments of TM impurities in the GaAs host are calculated under the assumption that orbital moments of TM are quenched and the total magnetization is due to spill ordering of electrons in the crystal. Thermodynamic possibility of formation of complexes between TM-atoms is investigated.
  •  
38.
  • Johannesson, Henrik, 1953, et al. (författare)
  • Conformal field theory approach to the two-channel Anderson model
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; 272-276:SUPPL. 1
  • Tidskriftsartikel (refereegranskat)abstract
    • The two-channel Anderson impurity model serves as a prototype for describing heavy-fermion materials with a possible mixed-valent regime with both quadrupolar and magnetic character. We report on the low-energy physics of the model, using a conformal field theory approach with exact Bethe Ansatz results as input.
  •  
39.
  • Jonsson, P, et al. (författare)
  • Nonlinear dynamic susceptibilities of interacting and noninteracting magnetic nanoparticles
  • 2000
  • Ingår i: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. - : ELSEVIER SCIENCE BV. - 0304-8853. ; 222:1-2, s. 219-226
  • Tidskriftsartikel (refereegranskat)abstract
    • The linear and cubic dynamic susceptibilities of solid dispersions of nanosized maghemite gamma -Fe2O3 particles have been measured for three samples with a volume concentration of magnetic particles ranging from 0.3% to 17%, in order to study the effect
  •  
40.
  • Jonsson, P, et al. (författare)
  • Spin-glass-like transition in a highly concentrated Fe-C nanoparticle system
  • 2001
  • Ingår i: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. - : ELSEVIER SCIENCE BV. - 0304-8853. ; 226, s. 1315-1316
  • Tidskriftsartikel (refereegranskat)abstract
    • A highly concentrated (17 vol%)Fe-C nano particle system, with a narrow size distribution d = 5.4 +/- 0.4 nm, has been investigated using magnetic AC susceptibility measurements covering a wide range of frequencies (17-170 Hz). A dynamic scaling analysis
  •  
41.
  • Kahl, Sören, et al. (författare)
  • Evolution of properties of epitaxial bismuth iron garnet films with increasing thickness
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 278:1-2, s. 244-255
  • Tidskriftsartikel (refereegranskat)abstract
    • Bismuth iron garnet (BIG) films of thicknesses from 470 to 2560 nm were prepared by pulsed laser deposition under identical deposition conditions. All films are epitaxial, bismuth deficient, and show rms surface roughnesses between 15 and 40 nm. X-ray coherence lengths decrease with increasing film thickness. Films below approximately 1 pm are free of cracks, thicker films possess a network of cracks. From fits of optical transmission spectra, real and imaginary parts of the refractive indices were found for wavelengths from 500 to 850 nm. The effects of thin film interference and surface roughness were included. With these data as input information, each of our experimental Faraday rotation spectra was described by a single diamagnetic line in visible light. The measured spectra could be reproduced and parameters of the magneto-optical transition were obtained. We observed a broadening of the transition with increasing film thickness and a red shift of the center frequency. This corresponds to our experimental observation that the wavelength of maximum Faraday rotation for BIG films in visible light shifts to longer wavelengths by almost 40 nm for a 2560-nm-thick film as compared to a 470-nm-thick film. As BIG is not thermodynamically stable, aging is a crucial question. We found that careful annealing in oxygen below the deposition temperature increases the angle of Faraday rotation, while film properties deteriorate during long annealing times at the deposition temperature.
  •  
42.
  • Kalska, B, et al. (författare)
  • Layer-resolved magnetic moments for Fe in a Co/Fe (001) superlattice
  • 2001
  • Ingår i: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. - : ELSEVIER SCIENCE BV. - 0304-8853. ; 226, s. 1773-1775
  • Tidskriftsartikel (refereegranskat)abstract
    • From the Mossbauer spectrum of a high-quality Fe/Co superlattice, the interface quality was ascertained by comparison of the details of the spectrum with the published value of the magnetic hyperfine held for iron in cobalt and no detectable roughness/int
  •  
43.
  • Kalska, B, et al. (författare)
  • The influence of V and Fe thicknesses on the Fe magnetic exchange in Fe/V multilayers
  • 2001
  • Ingår i: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. - : ELSEVIER SCIENCE BV. - 0304-8853. ; 226, s. 1782-1784
  • Tidskriftsartikel (refereegranskat)abstract
    • The Fe hyperfine field distribution in Fe(xML)/V(yML) with x=5 and 10 and y=5,10 and 14 has been determined. A strong dependence in Fe magnetic field distribution as a function of thickness V as well as Fe layers has been found. (C) 2001 Elsevier Science
  •  
44.
  • Kazakova, O., et al. (författare)
  • Influence of interfaces on the magnetic properties of submicron elements
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; 272-276:III, s. 1640-1641
  • Tidskriftsartikel (refereegranskat)abstract
    • We investigate the influence of interfaces on the properties of patterned elliptical elements made of epitaxial (BCC) Fe2/Co6 multilayers and polycrystalline Fe25Co75 alloy films, both containing 75 at% Co. Magnetic force microscopy shows that the formation of stable single domains in zero field is more likely in ellipses made of the alloy than of the multilayers. Magnetization measurements demonstrate considerably different behaviour of elements made of homogeneous and layered films, which imply that the magnetization reversal occurs through the formation of quasi-single domain states in the Fe25/Co75 ellipses and mainly by gradual rotation and switching in the FeCo elements.
  •  
45.
  • Le, Bacq O, et al. (författare)
  • First principles calculations of the magnetic profiles of the Fe-V multilayers
  • 2001
  • Ingår i: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. - : ELSEVIER SCIENCE BV. - 0304-8853. ; 226, s. 1722-1724 Language: English
  • Tidskriftsartikel (refereegranskat)abstract
    • The dependence of the magnetic moments of the Fe-V multilayers with respect to the thickness of the Fe region is investigated using first principles spin-polarized and fully relativistic electronic structure calculations, based upon the Full-Potential-Lin
  •  
46.
  • Lizárraga, Raquel, et al. (författare)
  • On the magnetic structure of TlCo2Se2
  • 2004
  • Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 272:557, s. 272-276
  • Tidskriftsartikel (refereegranskat)abstract
    • The magnetic properties of TlCo2Se2 have been investigated by means of first principles calculations. The magnetism of this compound is dominated by the contribution from the Co atoms, which form layers with a square coordination. The magnetic moments are arranged ferromagnetically within the ab-plane and in a non-collinear manner between consecutive planes.
  •  
47.
  • Lundin, U, et al. (författare)
  • On the validity region of Fermi-liquid description of 3D strongly correlated systems
  • 2001
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 226, s. 241-243
  • Tidskriftsartikel (refereegranskat)abstract
    • The decay of quasiparticles in systems with strongly correlated electrons (SSCE) is investigated. The difference with normal Fermi-liquid (FL) behavior is caused by kinematic interactions, The latter originate (in SSCE) from hopping and mixing interaction which in normal FL just modify bands, but do not cause a decay. Using a diagram technique we derive the lowest-order contribution giving decay and show how it varies with filling and with the position of the Fermi level with respect to the upper Hubbard's sub-band. Examples are given for a simple-cubic 3D-lattice. Due to spin dependence of the vertex functions a big effect on the lifetime of the quasi-particles due to magnetic fields is expected. A possible experimental realization is discussed. (C) 2001 Elsevier Science B.V. All rights reserved.
  •  
48.
  • Lundin, U, et al. (författare)
  • On the validity region of Fermi-liquid description of 3D strongly correlated systems
  • 2001
  • Ingår i: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. - : ELSEVIER SCIENCE BV. - 0304-8853. ; 226, s. 241-243 Language: English
  • Tidskriftsartikel (refereegranskat)abstract
    • The decay of quasiparticles in systems with strongly correlated electrons (SSCE) is investigated. The difference with normal Fermi-liquid (FL) behavior is caused by kinematic interactions, The latter originate (in SSCE) from hopping and mixing interaction
  •  
49.
  • Mathieu, R, et al. (författare)
  • Magnetotransport in a bi-crystal film of La0.7Sr0.3MnO3
  • 2001
  • Ingår i: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. - : ELSEVIER SCIENCE BV. - 0304-8853. ; 226, s. 786-787
  • Tidskriftsartikel (refereegranskat)abstract
    • Transport properties of an epitaxial film of La0.7Sr0.3MnO3 (LSMO), deposited epitaxially on a LaAlO3 bi-crystal substrate having a misorientation angle of 9.2 degrees, have been studied. The film was patterned into a meander containing 100 grain boundari
  •  
50.
  • Nam, DNH, et al. (författare)
  • Effects of Mg-doping in Nd0.7Sr0.3Mn1-yMgyO3(y <= 0.3)
  • 2001
  • Ingår i: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. - : ELSEVIER SCIENCE BV. - 0304-8853. ; 226, s. 1340-1342
  • Tidskriftsartikel (refereegranskat)abstract
    • The magnetic transition temperature, T-c, of Nd0.7Sr0.3Mn1-yMgyO3 decreases with increasing y. In between y = 0.1 and 0.2 the system undergoes a transition from being conducting and ferromagnetic to become insulating and spin glass like. This study is foc
  •  
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