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MA: Fachverband Magnetismus

MA 15: Spin structures and Magnetic Phase Transitions

MA 15.11: Vortrag

Dienstag, 1. April 2014, 12:15–12:30, HSZ 403

Studying finite-temperature magnetism using relativistic disordered local moment theory — •Andras Deak¹, Eszter Simon¹, Manuel dos Santos Dias², Laszlo Szunyogh¹, and Julie B. Staunton³ — ¹Department of Theoretical Physics, Budapest University of Technology and Economics, Budapest, Hungary — ²Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, Jülich, Germany — ³Department of Physics, University of Warwick, United Kingdom

Numerical investigations of magnetic phenomena at finite temperatures are mostly based on Heisenberg-type spin models treated with methods of statistical physics (Monte Carlo or Langevin dynamics simulations). Although the parameters of such models can be obtained from first principles calculations, neglecting higher-order spin interactions and longitudinal spin fluctuations may impose drastic restrictions on the applicability of such approaches.

In this talk we present a ``first principles only'' approach to studying finite-temperature magnetism. The method is based on the Disordered Local Moment (DLM) picture that can be merged efficiently with the Local Spin-Density Functional Approximation (LSDA) of Density Functional Theory (DFT). In particular, solving the Kohn--Sham--Dirac equation allows for investigating relativistic effects. We demonstrate the new computational scheme for the temperature dependence of the magnetocrystalline anisotropy energy of chemically ordered and disordered bulk FePt alloys, and the metamagnetic phase transition in bulk FeRh from antiferromagnetic to ferromagnetic phase.