Prediction of the Curie temperature considering the dependence of the phonon free energy on magnetic states  

作　　者：Tomonori Tanaka Yoshihiro Gohda 

机构地区：[1]Department of Materials Science and Engineering,Tokyo Institute of Technology,Yokohama 226-8502,Japan

出　　处：《npj Computational Materials》2020年第1期140-146,共7页计算材料学（英文）

基　　金：This work was supported by MEXT as Programme for Promoting Researches on the Supercomputer Fugaku(DPMSD),ESICMM Grant No.JPMXP0112101004,CREST-JST Grant No.JPMJCR18J1,JSPS-KAKENHI Grant No.17K04978,and CSRN in Osaka University;The calculations were partly carried out by using supercomputers at ISSP,The University of Tokyo,and TSUBAME,Tokyo Institute of Technology as well as the K computer,RIKEN(Project No.hp190169).

摘　　要：Prediction of the Curie temperature is of significant importance for the design of ferromagnetic materials.One of the most widely used methods to estimate the Curie temperature from first principles relies on a spin Hamiltonian,for example,the Heisenberg Hamiltonian,and exchange coupling parameters obtained by first-principles calculations at zero temperature.Even though there have been attempts to include the effects of magnetism on phonons,the influence of magnetism-dependent phonons on magnetism has been disregarded in the theoretical estimation of the Curie temperature.Here,we propose a first-principles thermodynamic approach to minimise the total free energy considering both the influences of magnetism on phonons and the feedback effect from phonons to magnetism.By applying our scheme to body-centered cubic Fe,we find a significant reduction of the Curie temperature due to the feedback effect.This result indicates the importance of the feedback effect for a quantitative description of finite-temperature magnetism.In addition,we point out that the reduction in the theoretical Curie temperature arises in a wide range of ferromagnetic materials that exhibit phonon softening due to magnetic disordering.

关 键 词：TEMPERATURE effect PHONON 

分 类 号：O57[理学—粒子物理与原子核物理]