Exchange parameters and adiabatic magnon energies from spin-spiral calculations

Jacobsson, Adam; Sanyal, Biplab; Blügel, Stefan

doi:10.1103/physrevb.88.134427

Cited by 39 publications

(39 citation statements)

References 33 publications

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“…The simple rock-salt structure along with the inability of regular DFT functionals to correctly describe these materials, make NiO and MnO typical benchmark systems to test methods for the calculation of exchange interactions in strongly correlated systems. Beyond the DFT methods such as LDA+U, [34,44,45] hybrid functionals, [46,47] the self-interaction correction, [41,48] GW approximation [49] and dynamical mean-field theory [42,50] have been used successfully to improve the correspondence between calculations and experiments in these materials. [34,42,46,47] In contrast, LSIC overestimates the electron localization, leading to a slight underestimation of the exchange interactions.…”

Section: Niomentioning

confidence: 99%

Exchange interactions in transition metal oxides: the role of oxygen spin polarization

Logemann¹,

Руденко²,

Katsnelson³

et al. 2017

J. Phys.: Condens. Matter

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Abstract. Magnetism of transition metal (TM) oxides is usually described in terms of the Heisenberg model, with orientation-independent interactions between the spins. However, the applicability of such a model is not fully justified for TM oxides because spin polarization of oxygen is usually ignored. In the conventional model based on the Anderson principle, oxygen effects are considered as a property of the TM ion and only TM interactions are relevant. Here, we perform a systematic comparison between two approaches for spin polarization on oxygen in typical TM oxides. To this end, we calculate the exchange interactions in NiO, MnO, and hematite (Fe 2 O 3 ) for different magnetic configurations using the magnetic force theorem. We consider the full spin Hamiltonian including oxygen sites, and also derive an effective model where the spin polarization on oxygen renormalizes the exchange interactions between TM sites. Surprisingly, the exchange interactions in NiO depend on the magnetic state if spin polarization on oxygen is neglected, resulting in non-Heisenberg behavior. In contrast, the inclusion of spin polarization in NiO makes the Heisenberg model more applicable. Just the opposite, MnO behaves as a Heisenberg magnet when oxygen spin polarization is neglected, but shows strong non-Heisenberg effects when spin polarization on oxygen is included. In hematite, both models result in non-Heisenberg behavior. General applicability of the magnetic force theorem as well as the Heisenberg model to TM oxides is discussed.

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Section: Niomentioning

confidence: 99%

Exchange interactions in transition metal oxides: the role of oxygen spin polarization

Logemann¹,

Руденко²,

Katsnelson³

et al. 2017

J. Phys.: Condens. Matter

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“…In order to obtain the adiabatic magnon dispersion, [54][55][56][57] we set up the spin-wave dynamical matrix ∆(q) at a Brillouin zone point q and solve for eigenvalues which provides the magnon frequencies:…”

Section: B Exchange Constants and Spin-wave Dispersionmentioning

confidence: 99%

First-principles calculations of exchange interactions, spin waves, and temperature dependence of magnetization in inverse-Heusler-based spin gapless semiconductors

et al. 2015

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Employing first principles electronic structure calculations in conjunction with the frozen-magnon method we calculate exchange interactions, spin-wave dispersion, and spin-wave stiffness constants in inverse-Heusler-based spin gapless semiconductor (SGS) compounds Mn2CoAl, Ti2MnAl, Cr2ZnSi, Ti2CoSi and Ti2VAs. We find that their magnetic behavior is similar to the half-metallic ferromagnetic full-Heusler alloys, i.e., the intersublattice exchange interactions play an essential role in the formation of the magnetic ground state and in determining the Curie temperature, Tc. All compounds, except Ti2CoSi possess a ferrimagnetic ground state. Due to the finite energy gap in one spin channel, the exchange interactions decay sharply with the distance, and hence magnetism of these SGSs can be described considering only nearest and next-nearest neighbor exchange interactions. The calculated spin-wave dispersion curves are typical for ferrimagnets and ferromagnets. The spin-wave stiffness constants turn out to be larger than those of the elementary 3d-ferromagnets. Calculated exchange parameters are used as input to determine the temperature dependence of the magnetization and Tc of the SGSs. We find that the Tc of all compounds is much above the room temperature. The calculated magnetization curve for Mn2CoAl as well as the Curie temperature are in very good agreement with available experimental data. The present study is expected to pave the way for a deeper understanding of the magnetic properties of the inverse-Heusler-based SGSs and enhance the interest in these materials for application in spintronic and magnetoelectronic devices.

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“…The perturbation of the spin state from the ordered magnetic ground state with a small θ (low-lying) could be considered as the magnetic quantized mode or magnon. The total energy difference between the perturbed spin spirals and the ferromagnetic states of the system containing the single magnetic atom per unit cell, ΔE q , θ can be attributed to the magnon energy (ω q (V)) of the system (Kübler, 2006;Jacobsson et al, 2013): (3) where M(V) is the volume dependent magnetic moment.…”

Section: Materials and Methods Theory And Computational Methodsmentioning

confidence: 99%

“…An extremely high fixed cone angle, e.g., θ = 90°, implies a large spin state perturbation. This could change the magnitude of the atomic spin moment of each cone angle state (Jacobsson et al, 2013). The expansion of DFT total energy of each spin spiral state via Heisenberg model is valid under the assumption of constant atomic spin moment.…”

Section: Introductionmentioning

confidence: 99%

Revisited Stress-Dependent Curie-Temperature in BCC Iron: LSDA+U Cleansing of Magnon Ambiguities

Kanchiang¹,

Pramchu²,

Jareonjittichai³

et al. 2017

CMUJNS

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This study proposes that the strong correlation of the 3d electrons in Fe is an important key to understanding the stress dependence behavior of Curie temperature (T c ). We proved our proposed hypothesis using density functional theory (DFT) within an LSDA+U (local spin density approximation +U) framework. Applying LSDA+U correction increased both the magnetic moment and magnon energy. The increased magnon energy directly contributed to the higher magnitude of the calculated T c (compared with LSDA). The acquired T c (from LSDA and LSDA+U) decreased with increasing unit cell volume; this was consistent with previous studies. Although introducing an on-site Coulomb interaction yielded the same stress dependence trend of T c compared with the LSDA results, increasing the T c magnitude was more reasonable under meanfield approximation, suggesting that the strong interaction of the 3d electrons in Fe influenced this phenomenon.

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Exchange parameters and adiabatic magnon energies from spin-spiral calculations

Cited by 39 publications

References 33 publications

Exchange interactions in transition metal oxides: the role of oxygen spin polarization

Exchange interactions in transition metal oxides: the role of oxygen spin polarization

First-principles calculations of exchange interactions, spin waves, and temperature dependence of magnetization in inverse-Heusler-based spin gapless semiconductors

Revisited Stress-Dependent Curie-Temperature in BCC Iron: LSDA+U Cleansing of Magnon Ambiguities

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