Finite-temperature magnetism in bcc Fe under compression.

Interatomic exchange interactions for finite-temperature magnetism and nonequilibrium spin dynamics.

We derive ab inito exchange parameters for general noncollinear magnetic configurations, in terms of a multiple scattering formalism. We show that the general exchange formula has an anisotropiclike term even in the absence of spin-orbit coupling, and that this term is large, for instance, for collinear configuration in bcc Fe, whereas for fcc Ni it is quite small. We demonstrate that keeping t...

Quantum-well states and induced magnetism in Fe/CuN/Fe bcc (001) trilayers.

Constitutive equations for modeling non-Schmid effects in single crystal bcc-Fe at low and ambient temperatures

Constitutive equations are developed for single crystal bcc-Fe at low and ambient temperatures based on the assumption that non-Schmid effects are primarily influential on orientation dependence and tension–compression asymmetry of the initial yield stress. Temperature dependence of the non-Schmid parameters is extracted from a fit to available experimental data. Constitutive models are also de...

Curie temperatures of fcc and bcc nickel and permalloy: Supercell and Green’s function methods

The finite-temperature magnetism of Ni and permalloy in body-centered-cubic bcc and face-centered-cubic fcc phases is studied theoretically using ab initio supercell calculations and Green’s function methods. The results confirm and explain the general experimental trend that the fcc phases have higher Curie temperatures than the bcc counterparts. In addition, the spin-wave stiffness constants ...

Structures and Phase Transitions

The properties of iron under extreme conditions are intensively studied [1] due to its relevance for geophysical models of the earth’s interior. From a more general point of view, the behaviour of bcc iron under compression is interesting since almost half of the elements contain the bcc structure in their phase diagram. The phonon dispersion of bcc elements was studied in the past in search of...