| 1. |
- Fleck, M., et al.
(författare)
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Magnetism near the Van Hove singularity
- 1998
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Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853. ; 177-181, s. 599-601
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Tidskriftsartikel (refereegranskat)abstract
- We study the phase diagrams of the s-band and d-band Hubbard model in two dimensions including electron correlations. While the ferromagnetic instability in the s-band case occurs only near the Van Hove singularity, ferromagnetism is more stable in the d-band model, and the values of the Stoner parameters in transition metals are reduced below their LDA values.(14 refs)
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| 2. |
- Hanson, Maj, 1939, et al.
(författare)
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Magnetic properties of epitaxial Ni(001) films and sub-micron particles
- 2001
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Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 236, s. 139-50
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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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| 3. |
- Uriarte, J L, et al.
(författare)
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Properties of FeNiB-based metallic glasses with primary BCC and FCC crystallisation products.
- 2003
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Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853. ; 254-255, s. 532-534
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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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| 4. |
- Adachi, N., et al.
(författare)
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Magnetic properties of single crystal film Bi3Fe5O12 prepared onto Sm3(Sc, Ga)5O12(111)
- 2002
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Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 242:Part 2, s. 775-777
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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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| 5. |
- Andersson, P. H., et al.
(författare)
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The effect of hydrogenation on the crystal structure and magnetic state in Pd3Mn
- 2001
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Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 226-230:Part 1, s. 1040-1041
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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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| 6. |
- AYADI, M, et al.
(författare)
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SPIN-GLASS FREEZING IN CD1-XMNXTE
- 1986
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 54-7, s. 1223-1224
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Tidskriftsartikel (refereegranskat)
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| 7. |
- BAJOREK, A, et al.
(författare)
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ON EXCHANGE MECHANISM IN HG1-XMNXS
- 1994
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Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 131, s. 363-368
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic susceptibility of Hg0.95Mn0.05S and Hg0.90Mn0.10S was measured by the SQUID technique. The experimental data were compared with the extended nearest neighbour pair approximation (ENNPA) calculation. The long range exchange interaction J = J(NN)R(-n), with the exponent n = 4, was found for both samples. The nearest neighbour exchange integral J(NN) was found to be around two times smaller than the effective exchange integral J(eff). The small value of the exponent n, which is a characteristic of the narrow gap semimagnetic semiconductors (SMSC’s), as well as the small J(NN)/J(eff) ratio, show the importance of a long-range exchange mechanism.
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| 8. |
- Batlle, X., et al.
(författare)
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The oxidation state at tunnel junction interfaces
- 2003
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Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 260:02-jan, s. 78-83
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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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| 9. |
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| 10. |
- CHIRWA, M, et al.
(författare)
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MAGNETIC SPECIFIC-HEAT OF FEF2 NEAR TN
- 1980
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 15-8, s. 457-458
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Tidskriftsartikel (refereegranskat)
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