Realistic magnetic thermodynamics by local quantization of a semiclassical Heisenberg model  

作　　者：Flynn Walsh Mark Asta Lin-Wang Wang 

机构地区：[1]Materials Sciences Division,Lawrence Berkeley National Laboratory,Berkeley,CA,94720,USA [2]Graduate Group in Applied Science and Technology,University of California,Berkeley,CA,94720,USA [3]Department of Materials Science and Engineering,University of California,Berkeley,CA,94720,USA [4]Institute of Semiconductors,Chinese Academy of Sciences,100083,Beijing,China

出　　处：《npj Computational Materials》2022年第1期1771-1776,共6页计算材料学（英文）

基　　金：F.W.was supported by the U.S.Department of Defense through the National Defense Science and Engineering Graduate Fellowship Program;M.A.and L.-W.W.were supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,Materials Sciences and Engineering Division,under Contract No.DE-AC02-05-CH11231(Materials Project program KC23MP and Non-Equilibrium Magnetic Materials program MSMAG,respectively);Computational resources were provided by award BES-ERCAP0021088 of the National Energy Research Scientific Computing Center(NERSC),a U.S.Department of Energy Office of Science User Facility at Lawrence Berkeley National Laboratory,operated under the same contract.

摘　　要：Classical Monte Carlo simulation of the Heisenberg model poorly describes many thermodynamic phenomena due to its neglect of the quantum nature of spins.Alternatively,we discuss how to semiclassically approach the quantum problem and demonstrate a simple method for introducing a locally approximate form of spin quantization.While the procedure underestimates magnetic short-range order,our results suggest a simple correction for recovering realistic spin–spin correlations above the critical temperature.Moreover,ensemble fluctuations are found to provide reasonably accurate thermodynamics,largely reproducing quantum mechanically calculated heat capacities and experimental magnetometry for ferromagnetic Fe and antiferromagnetic RbMnF3.Extensions of the method are proposed to address remaining inaccuracies.

关 键 词：temperature THERMODYNAMICS HEISENBERG 

分 类 号：O41[理学—理论物理]