| 1. |
- Fleck, M., et al.
(författare)
-
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
-
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
-
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
-
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)
-
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
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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)
-
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)
-
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
-
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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| 11. |
- Colarieti-Tosti, M., et al.
(författare)
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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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| 12. |
- 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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| 13. |
- 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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| 14. |
- 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
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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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| 15. |
- 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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| 16. |
- Ginnarsson, K., et al.
(författare)
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Equilibrium and nonequilibrium magnetic behaviour of a reentrant Ising spin glass.
- 1992
-
Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 104-107:3, s. 1607-1608
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Tidskriftsartikel (refereegranskat)abstract
- The reentrant Ising spin glass Fe0.62Mn0.38TiO3 has been investigated using SQUID magnetometry. The system is antiferromagnetic below TN(H = 0) = 33 K, and enters a mixed antiferromagnetic/spin glass phase below Tg(H = 0) = 25.8 K. Within the concept of a recent mean field model, a ratio TN(0)/Tg(0) close to unity indicates both intra- and interlayer frustration. The existence of an overlap length, lΔT, below which equilibrium spin correlations at temperatures T and T + ΔT are indistinguishable has been verified by magnetic relaxation experiments on this spin glass system
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| 17. |
- GRANBERG, P, et al.
(författare)
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NONEQUILIBRIUM RELAXATION IN A CU(MN) SPIN-GLASS
- 1990
-
Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 92, s. 228-232
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Tidskriftsartikel (refereegranskat)abstract
- The zero-field dynamics of a Cu(10 at% Mn) spin glass system has been investigated by means of zero-field-cooled magnetization measurements. By subjecting the sample to specific temperature variations just before the field application, new information about the nature of the spin glass phase is obtained. The results are in accord with some predictions from domain theories on the behaviour of the magnetic relaxation in spin glasses. Specifically, the experimental results support the prediction that the spin glass dynamics is governed by an interplay between a growing domain size and the overlap length.
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| 18. |
- Hanson, Maj, et al.
(författare)
-
A magnetic phase transition studied with high TC SQUIDs
- 1998
-
Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 177, s. 519-520
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Tidskriftsartikel (refereegranskat)abstract
- We have used high-Tc SQUIDs to study the phase transition in a film of Mn3O4. The film was positioned on top of the SQUID, and the temperature of the film and the SQUID was varied in the range 30-60 K. By monitoring the voltage at the SQUID output we were able to observe a reproducable shift in the SQUID response in the range 30-50 K. This shift is related to the transition from the paramagnetic to the ferrimagnetic state of the Mn3O4 film.
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| 19. |
- Hanson, Maj, et al.
(författare)
-
Interaction effects in the dynamic response of magnetic liquids
- 1991
-
Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 101, s. 45-46
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic susceptibility of magnetic liquids has been measured for frequencies up to 70 MHz. The imaginary part of the susceptibility exhibits a maximum around 10 MHz. This feature is interpreted as due to single-particle Néel relaxation, where particle interactions cause a slight concentration dependence in the position of the maximum.
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| 20. |
- Johansson, Christer, et al.
(författare)
-
The magnetization of magnetic liquids containing amorphous Fe1-xCx particles
- 1993
-
Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 122, s. 125-128
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Tidskriftsartikel (refereegranskat)abstract
- The magnetization of amorphous Fe1-xCx particles in decalin was measured in magnetic fields up to 12 T at temperatures between 10 and 250 K. For particles with a diameter of 3.2 nm, the zero field cooled magnetization has a maximum at 20 K. This is interpreted as a blocking of the superparamagnetic relaxation of single particles.
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| 21. |
- 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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| 22. |
- 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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| 23. |
- 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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| 24. |
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| 25. |
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| 26. |
- MATTSSON, J, et al.
(författare)
-
AGING IN A 2-DIMENSIONAL CUMN SPIN-GLASS
- 1992
-
Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 104, s. 1623-1624
-
Tidskriftsartikel (refereegranskat)abstract
- Utilizing zero-field cooled magnetization measurements the nonequilibrium dynamics in a 2D spin glass film is investigated. The experiments show that aging is an inherent property of 2D spin glass systems with qualitatively similar features as in 3D systems.
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| 27. |
- MATTSSON, J, et al.
(författare)
-
DETERMINATION OF THE CRITICAL EXPONENT-BETA FROM MEASUREMENTS OF A WEAK SPONTANEOUS MAGNETIZATION IN THE 3D ISING ANTIFERROMAGNET FEF2
- 1994
-
Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 136
-
Tidskriftsartikel (refereegranskat)abstract
- The critical exponent for the order parameter, beta, has been determined from the temperature dependence of a weak spontaneous magnetisation that appears below the Neel temperature in the prototypical 3d Ising antiferromagnet FeF2. The derived value of beta = 0.325 +/- 0.002 agrees with the theoretically calculated value for beta of a 3d Ising system. The very occurrence of a spontaneous magnetisation in pure FeF2 is assumed to be of piezomagnetic origin.
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| 28. |
- MATTSSON, J, et al.
(författare)
-
MULTILAYERED SPIN-GLASS FILMS - SENSITIVE PROBES OF RKKY
- 1992
-
Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 104, s. 1619-1620
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Tidskriftsartikel (refereegranskat)abstract
- A new method that uses superstructures of Cu(Mn) spin glass films separated by metallic interlayers to probe the decay with thickness of the RKKY interaction within the interlayers is discussed.
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| 29. |
- MATTSSON, J, et al.
(författare)
-
NONLINEAR SUSCEPTIBILITY OF 2D SPIN-GLASS FILMS
- 1992
-
Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 104, s. 1621-1622
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Tidskriftsartikel (refereegranskat)abstract
- A careful study of the nonlinear susceptibility of multilayered two-dimensional Cu(14 at% Mn) spin glass layers separated by thick interlayers of Cu is reported. The experiments were performed in SQUID magnetometers using an ac susceptibility technique in the field range 0-0.5 kG and dc magnetization measurements in the field range 0-10 kG. The static 2D critical exponents have been determined from scaling analyses.
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| 30. |
- Mikhailova, M., et al.
(författare)
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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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| 31. |
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| 32. |
- NORDBLAD, P, et al.
(författare)
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CD0.6MN0.4TE, A SEMICONDUCTING SPIN-GLASS
- 1986
-
Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 59, s. 250-254
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Tidskriftsartikel (refereegranskat)
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| 33. |
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| 34. |
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| 35. |
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| 36. |
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| 37. |
- PremKumar, R., et al.
(författare)
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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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| 38. |
- SPASOJEVIC, V, et al.
(författare)
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MAGNETIC-SUSCEPTIBILITY OF THE SEMIMAGNETIC SEMICONDUCTOR HG1-XMNXS
- 1993
-
Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 118, s. 152-158
-
Tidskriftsartikel (refereegranskat)abstract
- The magnetic susceptibility of Hg1-xMnxS (x = 0.05, 0.10, 0.20, 0.30) has been measured in a SQUID magnetometer (T = 2-250 K) in a magnetic field of 9 kG. The high-temperature susceptibility of Hg1-xMnxS was found to behave in accordance with the Curie-Weiss law. From chi(T) measurements, for the first time, the microscopic parameter J1/k(B) = -(6.3 +/- 0.1) K (effective exchange integral) has been obtained. A spin S = 2.48 +/- 0.09, close to its atomic value S = 5/2, was also found. Low-temperature susceptibility measurements show that the sample with the highest Mn-concentration (x = 0.30) exhibits a difference between field-cooled and zero-field-cooled susceptibility signalling a spin-glass phase transition at about 4 K. As Hg1-xMnxS is the last uninvestigated alloy from the A1-xIIMnxBVI group, a complete review of experimental values (J1/k(B)) is also given.
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| 39. |
- SRIVASTAVA, BK, et al.
(författare)
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REENTRANT SPIN-GLASS-LIKE BEHAVIOR OF (FE0.90CR0.05NI0.05)2P
- 1994
-
Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 132, s. 124-130
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Tidskriftsartikel (refereegranskat)abstract
- Di-iron phosphide with small substitutions of iron with Cr and Ni, (Fe0.90Cr0.05Ni0.05)2P, has been investigated by SQUID-magnetometry. The sample exhibits a first order ferromagnetic transition at T(c) almost-equal-to 180 K and a re-entrant spin glass transition at T(g) almost-equal-to 125 K. The ferromagnetic transition is severely smeared by weak applied magnetic fields. The re-entrant transition is evidenced from both dc-magnetisation and ac-susceptibility measurements. An aging phenomenon is observed at temperatures below T(g) and the freezing temperatures, T(f), and their corresponding relaxation times, tau scale according to conventional critical slowing down: tau/tau0 = ((T(f) - T(g))/T(g))-znu, with an exponent znu almost-equal-to 9, a value that is found also at ordinary paramagnetic to spin glass transitions.
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| 40. |
- 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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| 41. |
- 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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| 42. |
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| 43. |
- Urech, Mattias, et al.
(författare)
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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
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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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| 44. |
- Åkerman, Johan, et al.
(författare)
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Criteria for ferromagnetic-insulator-ferromagnetic tunneling
- 2002
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Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 240:03-jan, s. 86-91
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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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| 45. |
- Aakash, förnamn, et al.
(författare)
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Structural, magnetic and hyperfine characterizations of nanocrystalline Zn-Cd doped nickel ferrites
- 2017
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Ingår i: Journal of Magnetism and Magnetic Materials. - : ELSEVIER SCIENCE BV. - 0304-8853 .- 1873-4766. ; 441, s. 710-717
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Tidskriftsartikel (refereegranskat)abstract
- In our present work, we have synthesized a series of Cd-Zn doped nickel ferrite ((Cd-0.5 Zn-x(x)) Ni0(.5)Fe(2)O(4); x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) through standard chemical co-precipitation method to study the influence of diamagnetic ions (Cd, Zn) on the magnetic properties of ferrites. XRD and Raman spectroscopy were employed for the structural characterizations. The refinement of the X-ray diffractogram data augmented by the Williamson-Hall plots showed the presence of Cd2+ vacancies and a strained crystal structure. The vibrational spectroscopy indicated the presence of lower space-group symmetry and a distorted crystal structure. Magnetic measurements showed the samples possessed low magnetic anisotropy along with a canted spin structure. The Mossbauer measurements confirmed the cation distribution and gave evidence of super transferred hyperfine interactions arising due to canted spin structure of the system.
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| 46. |
- Abdu, Yassir, et al.
(författare)
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Coexisting antiferromagnetism and ferromagnetism in mechanically alloyed Fe-rich Fe-Ni alloys : Implications regarding the Fe-Ni phase diagram below 400 °C
- 2004
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 280:2-3, s. 395-403
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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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| 47. |
- Abdu, Yassir, et al.
(författare)
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Field induced local magnetic moments in gamma-fcc Fe-Ni anti-Invar alloys
- 2004
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Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 280, s. 243-250
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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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| 48. |
- Abrikosov, Igor, et al.
(författare)
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Magnetism in systems with reduced dimensionality and chemical disorder : the local environment effects
- 2006
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 300:1, s. 211-215
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Tidskriftsartikel (refereegranskat)abstract
- We study influence of the local chemical environment, the so-called local environment effects, on the electronic structure and properties of magnetic systems with reduced dimensionality and chemical disorder, and show that they play a crucial role in a vicinity of magnetic instability. As a model, we consider Fe–Ni Invar. We present results obtained from ab initio calculations of the electronic structure, magnetic moments, and exchange interactions in random fcc Fe–Ni alloy, for a single monolayer alloy film on a Cu (0 0 1) substrate as well as in the bulk. We analyze the difference between the film and the bulk magnetization, which is found to be most pronounced for dilute alloys. We also analyze a sensitivity of the individual magnetic moments and effective exchange parameters to the local chemical environment of the atoms.
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| 49. |
- Ahlberg, Martina, et al.
(författare)
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Temperature dependence of magnetic properties in weakly exchange coupled Fe/V superlattices
- 2013
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 341, s. 142-147
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Tidskriftsartikel (refereegranskat)abstract
- We use Fe(3)/V(x)Fe(3)/V(x) superlattices, x = 16-27 monolayers (ML) to explore the interlayer exchange coupling (IEC) as a function of both spacer layer thickness and temperature. Fe/V is a common model system for studies addressing the IEC, but the behavior in the weakly exchange coupled regime, complemented with the temperature dependence of the magnetic properties, have remained unexplored. We observe clear regions with ferro- and antiferromagnetic coupling, which is manifested in oscillations in the saturation field, the remanence and the critical temperature. The oscillation in the interlayer coupling (J') has a period of 5.8(1) ML. This is approximate to 0.8 ML smaller than observed for Fe(7)/V(x) superlattices which illustrates the influence of the magnetic layer thickness on the interlayer coupling. The temperature dependence of the remanent magnetization was proven to be significantly affected by the strength of the ferromagnetic coupling, leading to high values of the effective critical exponent beta(eff).
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| 50. |
- Ahniyaz, Anwar, et al.
(författare)
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Preparation of iron oxide nanocrystals by surfactant-free or oleic acid-assisted thermal decomposition of a Fe(III) alkoxide
- 2008
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 320:6, s. 781-787
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Tidskriftsartikel (refereegranskat)abstract
- A new non-hydrolytic, alkoxide-based route was developed to synthesize iron oxide nanocrystals. Surfactant-free thermal decomposition of the iron 2-methoxy-ethoxide precursors results in the formation of uniform iron oxide nanocrystals with an average size of 5.6 nm. Transmission electron microscope study shows that the nanocrystals are protected against aggregation by a repulsive surface layer, probably originating from the alkoxy-alkoxide ligands. Addition of oleic acid resulted in monodisperse nanocrystals with an average size of 4 nm. Mössbauer analysis confirmed that the nanocrystals mainly consisted of maghemite. Analysis of the magnetic hysteresis loop measurements and the zero field and field cooled measurements displayed an excellent fit to established theories for single-domain superparamagnetic nanocrystals and the size of the magnetic domains correlated well to the crystallite size obtained from transmission electron microscope.
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