Green’s function treatment of the localized antiferromagnetic system

Li, Qingan

doi:10.1103/physrevb.70.014406

Cited by 4 publications

(1 citation statement)

References 17 publications

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“…In reference [15], a ferromagnetic film is coupled to an antiferromagnetic layer; however, the orientation of the magnetization of the antiferromagnet is frozen. Other work considers an antiferromagnetic coupling between ferromagnetic layers [16,17,18].…”

Section: Introductionmentioning

confidence: 99%

Coupled ferro–antiferromagnetic Heisenberg bilayers investigated by many-body Green function theory

Fröbrich¹,

Kuntz²,

Jensen³

2005

J. Phys.: Condens. Matter

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Abstract. A theory of coupled ferro-and antiferromagnetic Heisenberg layers is developed within the framework of a many-body Green's function theory (GFT) that allows non-collinear magnetic arrangements by introducing sublattice structures. As an example, the coupled ferro-antiferromagnetic (FM-AFM) bilayer is investigated. We compare the results with those of bilayers with purely ferromagnetic or antiferromagnetic couplings. In each case we also show the corresponding results of mean field theory (MFT), in which magnon excitations are completely neglected. There are significant differences between GFT and MFT. A remarkable finding is that for the coupled FM-AFM bilayer the critical temperature decreases with increasing interlayer coupling strength for a simple cubic lattice, whereas the opposite is true for an fcc lattice as well as for MFT for both lattice types.

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Section: Introductionmentioning

confidence: 99%

Coupled ferro–antiferromagnetic Heisenberg bilayers investigated by many-body Green function theory

Fröbrich¹,

Kuntz²,

Jensen³

2005

J. Phys.: Condens. Matter

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Many-body Green's function theory of Heisenberg films

Fröbrich¹,

Kuntz²

2006

Physics Reports

162

135

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The treatment of Heisenberg films with many-body Green's function theory (GFT) is reviewed. The basic equations of GFT are derived in sufficient detail so that the rest of the paper can be understood without having to consult further literature. The main part of the paper is concerned with applications of the formalism to ferromagnetic, antiferromagnetic and coupled ferromagnetic-antiferromagnetic Heisenberg films based on a generalized Tyablikov (RPA) decoupling of the exchange interaction and exchange anisotropy terms and an Anderson-Callen decoupling for a weak single-ion anisotropy. We not only give a consistent description of our own work but also refer extensively to related investigations. We discuss in particular the reorientation of the magnetization as a function of the temperature and film thickness. If the single-ion anisotropy is strong, it can be treated exactly by going to higher-order Green's functions. We also discuss the extension of the theory beyond RPA. Finally the limitations of GFT is pointed out.Comment: 124 pages, 32 figures, accepted by Physics Report

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Exchange interactions and temperature dependence of magnetization in half-metallic Heusler alloys

et al. 2005

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We study the exchange interactions in half-metallic Heusler alloys using first-principles calculations in conjunction with the frozen-magnon approximation. The Curie temperature is estimated within both mean-field (MF) and random-phase-approximation (RPA) approaches. For the halfHeusler alloys NiMnSb and CoMnSb the dominant interaction is between the nearest Mn atoms. In this case the MF and RPA estimations differ strongly. The RPA approach provides better agreement with experiment. The exchange interactions are more complex in the case of full-Heusler alloys Co2MnSi and Co2CrAl where the dominant effects are the inter-sublattice interactions between the Mn(Cr) and Co atoms and between Co atoms at different sublattices. For these compounds we find that both MF and RPA give very close values of the Curie temperature slightly underestimating experimental quantities. We study the influence of the lattice compression on the magnetic properties. The temperature dependence of the magnetization is calculated using the RPA method within both quantum mechanical and classical approaches.

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Green’s function treatment of the localized antiferromagnetic system

Cited by 4 publications

References 17 publications

Coupled ferro–antiferromagnetic Heisenberg bilayers investigated by many-body Green function theory

Coupled ferro–antiferromagnetic Heisenberg bilayers investigated by many-body Green function theory

Many-body Green's function theory of Heisenberg films

Exchange interactions and temperature dependence of magnetization in half-metallic Heusler alloys

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