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We consider the two-band double exchange model for manganites with Jahn-Teller (JT) coupling and explore the suppression of the ferromagnetism because of the JT distortion. The localized spins of the $\emph{t}_{2g}$ electrons are…

Strongly Correlated Electrons · Physics 2012-07-31 Vasil Michev , Naoum Karchev

We present a data set of calculated Curie temperatures for the main-phase compounds of rare-earth permanent magnets. We employ ab initio electronic structure calculations for the itinerant ferromagnetism and an effective spin model for the…

Materials Science · Physics 2020-04-28 Munehisa Matsumoto , Hisazumi Akai

We introduce a Heisenberg Hamiltonian for describing the magnetic properties of GaMnAs. Electronic degrees of freedom are integrated out leading to a pairwise interaction between Mn spins. Monte Carlo simulations in large systems are then…

Materials Science · Physics 2009-11-10 L. Brey , G. Gómez-Santos

We present a theory to model carrier mediated ferromagnetism in concentrated or diluted local moment systems. The electronic subsystem of the Kondo lattice model is described by a combined equation of motion / coherent potential…

Strongly Correlated Electrons · Physics 2011-04-22 M. Stier , W. Nolting

We have verified that the variational mean field theory approach suggested by Narimanov and Varma (preprint cond-mat/0002191) being applied to the realistic two-band model provides a good agreement with experimental data for the Curie…

Strongly Correlated Electrons · Physics 2009-10-31 M. O. Dzero

The phase diagram of the multivalent manganites $\rm La_{1-x}Ca_xMnO_3$, in space of temperature and doping $x$, is a challenge for the theoretical physics. It is an important test for the model used to study these compounds and the method…

Strongly Correlated Electrons · Physics 2012-07-26 Vasil Michev , Naoum Karchev

Prediction of the Curie temperature is of significant importance for the design of ferromagnetic materials. Even though the Curie temperature has been estimated using the Heisenberg model, magnetic exchange coupling parameters widely used…

Materials Science · Physics 2020-12-08 Tomonori Tanaka , Yoshihiro Gohda

We present a model study of ferromagnetic films consisting of free Bloch electrons coupled to localized moments (Kondo lattice films). By mapping the local interaction onto an effective Heisenberg Hamiltonian we obtain temperature and…

Strongly Correlated Electrons · Physics 2007-05-23 Jochen Kienert , Wolfgang Nolting

The coexistence of ferromagnetism and metallic conduction in doped manganites has long been explained by a double-exchange model in which the ferromagnetic exchange arises from the carrier hopping. We evaluate the zero-temperature spin…

Strongly Correlated Electrons · Physics 2009-10-31 G. M. Zhao

We report the parameter-free, density functional theory calculations of interatomic exchange interactions and Curie temperatures of half-metallic ferrimagnetic full Heusler alloys Mn2VZ (Z=Al, Ge). To calculate the interatomic exchange…

Materials Science · Physics 2007-05-23 E. Sasioglu , L. M. Sandratskii , P. Bruno

A lattice spin-fermion model for diluted magnetic semiconductors (DMS) is investigated numerically, improving on previously used mean-field (MF) approximations. Curie temperatures are obtained varying the Mn-spin x and hole n densities, and…

Strongly Correlated Electrons · Physics 2009-11-07 Gonzalo Alvarez , Matthias Mayr , Elbio Dagotto

We use supercell and frozen-magnon approaches to study the dependence of the magnetic interactions in (Ga,Mn)As on the Mn concentration. We report the parameters of the exchange interaction between Mn spins and the estimates of the Curie…

Materials Science · Physics 2009-11-07 L. M. Sandratskii , P. Bruno

The surface magnetic phase transition of a double-exchange model for metallic manganites is studied using a Schwinger-boson mean-field method. About three unit-cells wide surface layers are identified. The magnetic moment in these layers…

Strongly Correlated Electrons · Physics 2015-05-13 Satoshi Okamoto

High-accuracy Swendsen and Wang Monte Carlo simulations were performed to study the Curie temperature of ferromagnetic, binary Ising systems on the square lattice. Our results are compared with mean-field like approaches. Based on these…

Condensed Matter · Physics 2007-05-23 Zoltan Neda

One-band Hubbard model with hopping parameter $t$ and Coulomb repulsion $U$ is considered at half filling. By means of the Schwinger bosons and slave Fermions representation of the electron operators and integrating out the spin-singlet…

Strongly Correlated Electrons · Physics 2015-06-04 Naoum Karchev

We compare three first-principles methods of calculating the Curie temperature in two-dimensional (2D) ferromagnetic materials (FM), modeled using the Heisenberg model, and propose a simple formula for estimating the Curie temperature with…

We present a theoretical survey of ferromagnetic transition temperatures in cubic (III,Mn)V semiconductors based on a model with $S=5/2$ local moments exchange-coupled to itinerant holes in the host semiconductor valence band. Starting from…

Materials Science · Physics 2016-08-16 T. Jungwirth , Jürgen König , Jairo Sinova , J. Kučera , A. H. MacDonald

Using the Swendsen and Wang algorithm, high accuracy Monte Carlo simulations were performed to study the concentration dependence of the Curie temperature in binary, ferromagnetic Ising systems on the simple-cubic lattice. Our results are…

Condensed Matter · Physics 2009-10-22 Zoltan NEDA

We investigate the influence of the Jahn-Teller distortion and a direct antiferromagnetic moment coupling as extensions to a two-band Kondo lattice model for the magnetic and electronic properties of manganites. Those are calculated…

Strongly Correlated Electrons · Physics 2007-05-23 Martin Stier , Wolfgang Nolting

The magnetic properties of a material are determined by a subtle balance between the various interactions at play, a fact that makes the design of new magnets a daunting task. High-throughput electronic structure theory may help to explore…

Materials Science · Physics 2019-10-16 James Nelson , Stefano Sanvito
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