Electronic structure, chemical bonding, and finite‐temperature magnetic properties of full Heusler alloys

Abstract

AbstractThe electronic structure, chemical bonding, and magnetic properties of 15 full Heusler alloys X2MnZ have been studied on the basis of density‐functional theory using the TB‐LMTO‐ASA approach and the local‐density (LDA), as well as the generalized‐gradient approximation (GGA). Correlations between the chemical bondings derived from crystal orbital Hamilton population (COHP) analysis and magnetic phenomena are obvious, and different mechanisms leading to spin polarization and ferromagnetism are derived. As long as a magnetically active metal atom X is present, antibonding XX and XMn interactions at the Fermi level drive the systems into the ferromagnetic ground state; only if X is nonmagnetic (such as in Cu2MnZ), antibonding MnMn interactions arise, which again lead to ferromagnetism. Finite‐temperature effects (Curie temperatures) are analyzed using a mean‐field description, and a surprisingly simple (or, trivial) relationship between structural properties (MnMn interatomic distances) and TC is found, being of semiquantitative use for the prediction of the latter. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 90–102, 2006