title: Finite-temperature magnetism in bcc Fe under compression.
abstract: We investigate the contributions of finite-temperature magnetic fluctuations to the thermodynamic properties of bcc Fe as functions of pressure. First, we apply a tight-binding total-energy model parameterized to first-principles linearized augmented plane-wave computations to examine various ferromagnetic, anti-ferromagnetic, and noncollinear spin spiral states at zero temperature. The tight-binding data are fit to a generalized Heisenberg Hamiltonian to describe the magnetic energy functional based on local moments. We then use Monte Carlo simulations to compute the magnetic susceptibility, the Curie temperature, heat capacity, and magnetic free energy. Including the finite-temperature magnetism improves the agreement with experiment for the calculated thermal expansion coefficients.
authors.affiliation: Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA.
authors.forename: Xianwei
authors.initials: X
authors.lastname: Sha
authors.forename: R E
authors.initials: RE
authors.lastname: Cohen
mesh_terms: D001274:Atmospheric Pressure; D005290:Ferric Compounds / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008280:Magnetics / Q000379:methods; D009010:Monte Carlo Method; D011312:Pressure; D013696:Temperature; D013816:Thermodynamics
chemical_list: D005290:Ferric Compounds; C001215:ferrite; D007501:Iron