Temperature-dependent Heisenberg exchange coupling constants from linking electronic-structure calculations and Monte Carlo simulations

摘要

We propose a method to calculate the temperature dependence of Heisenberg exchange coupling constant J_(ij). Within the formalism of disordered local moments (DLM), the magnetization and the J_(ij) are computed from first principles for any concentration c of the magnetic constituents. The exchange coupling constants are then used in Monte Carlo (MC) simulations to compute the temperature dependence of the magnetization for the given c. By comparing the magnetization from DLM calculations and from MC simulations we obtain a mapping of temperature versus concentration and eventually temperature-dependent J_(ij). The approach which is applied to bulk Fe and Co can for example improve critical exponents.