Magnetic Materials at finite Temperatures: thermodynamics and combined spin and molecular dynamics derived from first principles calculations

26th IUPAP Conference on Computational Physics

物理学;计算机科学

Eisenbach, Markus^1 ; Perera, Dilina^2 ; Landau, David P.^2 ; Nicholson, Don M.^3 ; Yin, Jungqi^4 ; Brown, Gregory^5

National Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge

TN

37831, United States^1

Center for Simulational Physics, University of Georgia, Athens

GA

30602, United States^2

Department of Physics, University of North Carolina, Asheville

NC

28804, United States^3

National Institute for Computational Sciences, University of Tennessee, Oak Ridge

TN

37831, United States^4

Department of Physics, Florida State University, Tallahassee

FL

32306, United States^5

关键词: Dynamic structure factors;    Dynamics calculations;    Effective potentials;    Experimental values;    Finite temperatures;    First principles;    First-principles calculation;    Magnon-Phonon interaction;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/640/1/012019/pdf
DOI  :  10.1088/1742-6596/640/1/012019

学科分类：计算机科学（综合）

来源: IOP

【 摘 要 】

We present a unified approach to describe the combined behavior of the atomic and magnetic degrees of freedom in magnetic materials. Using Monte Carlo simulations directly combined with first principles the Curie temperature can be obtained ab initio in good agreement with experimental values. The large scale constrained first principles calculations have been used to construct effective potentials for both the atomic and magnetic degrees of freedom that allow the unified study of influence of phonon-magnon coupling on the thermodynamics and dynamics of magnetic systems. The MC calculations predict the specific heat of iron in near perfect agreement with experimental results from 300K to above Tc and allow the identification of the importance of the magnon-phonon interaction at the phase-transition. Further Molecular Dynamics and Spin Dynamics calculations elucidate the dynamics of this coupling and open the potential for quantitative and predictive descriptions of dynamic structure factors in magnetic materials using first principles derived simulations.