Magnetic anisotropic effects and electronic correlations in MnBi ferromagnet

Antropov, Vladimir; Antonov, V. N.; Bekenov, L. V.; Kutepov, Andrey; Kotliar, Gabriel

doi:10.1103/physrevb.90.054404

Cited by 74 publications

(94 citation statements)

References 92 publications

(127 reference statements)

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“…Recently, however, the availability (and thus price) of the rare-earth elements became rather volatile, calling for development of replacement materials which would use less or none of * Corresponding author: jan.rusz@physics.uu.se the rare-earth elements. Intense research efforts have started worldwide, revisiting previously known materials, such as Fe 2 P [5][6][7], FeNi [8], or Fe 16 N 2 [9], doing computational data mining among the large family of Heusler alloys [10], exploring the effects of strain [11][12][13][14][15][16][17] and doping by interstitial elements [18,19], multilayers such as Fe/W-Re [20] or, as a limiting case of multilayers, the L1 0 family of compounds [21], or promising Mn-based systems [22][23][24][25][26][27], among others.…”

Section: Introductionmentioning

confidence: 99%

Magnetic properties of(Fe1−xCox)2Balloys and the effect of doping by
Edström¹,
Werwiński²,
Iuşan³
et al. 2015
Phys. Rev. B

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We have explored, computationally and experimentally, the magnetic properties of (Fe 1−x Co x ) 2 B alloys. Calculations provide a good agreement with experiment in terms of the saturation magnetization and the magnetocrystalline anisotropy energy with some difficulty in describing Co 2 B, for which it is found that both full potential effects and electron correlations treated within dynamical mean field theory are of importance for a correct description. The material exhibits a uniaxial magnetic anisotropy for a range of cobalt concentrations between x = 0.1 and x = 0.5. A simple model for the temperature dependence of magnetic anisotropy suggests that the complicated nonmonotonic behavior is mainly due to variations in the band structure as the exchange splitting is reduced by temperature. Using density functional theory based calculations we have explored the effect of substitutionally doping the transition metal sublattice by the whole range of 5d transition metals and found that doping by Re or W elements should significantly enhance the magnetocrystalline anisotropy energy. Experimentally, W doping did not succeed in enhancing the magnetic anisotropy due to formation of other phases. On the other hand, doping by Ir and Re was successful and resulted in magnetic anisotropies that are in agreement with theoretical predictions. In particular, doping by 2.5 at. % of Re on the Fe/Co site shows a magnetocrystalline anisotropy energy which is increased by 50% compared to its parent (Fe 0.7 Co 0.3 ) 2 B compound, making this system interesting, for example, in the context of permanent magnet replacement materials or in other areas where a large magnetic anisotropy is of importance.

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Section: Introductionmentioning

confidence: 99%

Magnetic properties of(Fe1−xCox)2Balloys and the effect of doping by
Edström¹,
Werwiński²,
Iuşan³
et al. 2015
Phys. Rev. B

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“…This anisotropic thermal expansion has been linked in a recent theoretical study to the magnetic anisotropy and spin reorientation in MnBi [28]. The important role played by the nominally nonmagnetic Bi atoms in the magnetism of MnBi also has been recently identified by first principles calculations [29], where the fine details of the Bi-Bi exchange interactions and spin-orbit coupling on Bi are demonstrated to influence strongly the magnetic anisotropy. Thus, atomic displacement parameters, as especially those of Bi, may provide a fundamental link between the temperature dependence of structural and magnetic properties, and could be a fruitful target for further theoretical investigations.…”

Section: B Neutron Diffractionmentioning

confidence: 99%

“…This is generally consistent with the lattice parameters reported here, where the abplane of the orthorhombic phase (moments in the plane) is contracted relative to the hexagonal phase (moments out of the plane). First principles calculations reported by Antropov et al [29] find that this is due to spin-orbit coupling and an unusual evolution of Bi−Bi interactions as the lattice constants change. Note that these calculations, and all others for MnBi reported to date, used the NiAs-structure at all temperatures.…”

Section: A X-ray Diffractionmentioning

confidence: 99%

“…While the hexagonal NiAs structure type describes the powder xray diffraction results at all temperatures, anomalies in both the a and c lattice parameters occur at temperatures near the spin reorientation. Recent first-principles calculations have reproduced these magneto-elastic effects, and linked the spin-reorientation to anisotropic thermal expansion [28], and in particular to resulting changes in the anisotropic pairwise exchange interactions between Bi p-states [29].…”

Section: Introductionmentioning

confidence: 99%

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Symmetry-lowering lattice distortion at the spin reorientation in MnBi single crystals

et al. 2014

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Structural and physical properties determined by measurements on large single crystals of the anisotropic ferromagnet MnBi are reported. The findings support the importance of magnetoelastic effects in this material. X-ray diffraction reveals a structural phase transition at the spin reorientation temperature TSR = 90 K. The distortion is driven by magneto-elastic coupling, and upon cooling transforms the structure from hexagonal to orthorhombic. Heat capacity measurements show a thermal anomaly at the crystallographic transition, which is suppressed rapidly by applied magnetic fields. Effects on the transport and anisotropic magnetic properties of the single crystals are also presented. Increasing anisotropy of the atomic displacement parameters for Bi with increasing temperature above TSR is revealed by neutron diffraction measurements. It is likely that this is directly related to the anisotropic thermal expansion in MnBi, which plays a key role in the spin reorientation and magnetocrystalline anisotropy. The identification of the true ground state crystal structure reported here may be important for future experimental and theoretical studies of this permanent magnet material, which have to date been performed and interpreted using only the high temperature structure.

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“…Q is a (N + 1) × (N + 1) symmetric quasiuniform tridiagonal canonical matrix that does not depend on material parameters (see Appendix A). In H n = H + εn, ε models external or anisotropy field gradients [21,22]. Since in general, matrices Q and diag {H n } cannot be diagonalized simultaneously, we introduce a new matrixQ = Q + (ε/J )diag{n} that satisfies J Q nm + H n δ nm = JQ nm + H δ nm .…”

Section: A Linear Spin-wave Theorymentioning

confidence: 99%

Energy repartition in the nonequilibrium steady state

2017

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The concept of temperature in nonequilibrium thermodynamics is an outstanding theoretical issue. We propose an energy repartition principle that leads to a spectral (mode-dependent) temperature in steady-state nonequilibrium systems. The general concepts are illustrated by analytic solutions of the classical Heisenberg spin chain connected to Langevin heat reservoirs with arbitrary temperature profiles. Gradients of external magnetic fields are shown to localize spin waves in a Wannier-Zeemann fashion, while magnon interactions renormalize the spectral temperature. Our generic results are applicable to other thermodynamic systems such as Newtonian liquids, elastic solids, and Josephson junctions.

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Magnetic anisotropic effects and electronic correlations in MnBi ferromagnet

Cited by 74 publications

References 92 publications

Magnetic properties of(Fe1−xCox)2Balloys and the effect of doping by
Edström¹,
Werwiński²,
Iuşan³
et al. 2015
Phys. Rev. B

Magnetic properties of(Fe1−xCox)2Balloys and the effect of doping by
Edström¹,
Werwiński²,
Iuşan³
et al. 2015
Phys. Rev. B

Symmetry-lowering lattice distortion at the spin reorientation in MnBi single crystals

Energy repartition in the nonequilibrium steady state

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Magnetic anisotropic effects and electronic correlations in MnBi ferromagnet

Cited by 74 publications

References 92 publications

Magnetic properties of(Fe1−xCox)2Balloys and the effect of doping byEdström1, Werwiński2, Iuşan3 et al. 2015Phys. Rev. B

Magnetic properties of(Fe1−xCox)2Balloys and the effect of doping byEdström1, Werwiński2, Iuşan3 et al. 2015Phys. Rev. B

Symmetry-lowering lattice distortion at the spin reorientation in MnBi single crystals

Energy repartition in the nonequilibrium steady state

Contact Info

Product

Resources

About

Magnetic properties of(Fe1−xCox)2Balloys and the effect of doping by
Edström¹,
Werwiński²,
Iuşan³
et al. 2015
Phys. Rev. B

Magnetic properties of(Fe1−xCox)2Balloys and the effect of doping by
Edström¹,
Werwiński²,
Iuşan³
et al. 2015
Phys. Rev. B