Electronic structure, magnetism, and disorder in the Heusler compound Co${}_2$TiSn

Abstract

Polycrystalline samples of the half-metallic ferromagnet Heusler compound Co${}_2$TiSn have been prepared and studied using bulk techniques (X-ray diffraction and magnetization) as well as local probes (${}^{119}$Sn Mössbauer spectroscopy and ${}^{59}$Co nuclear magnetic resonance spectroscopy) in order to determine how disorder affects half-metallic behavior and also, to establish the joint use of Mössbauer and NMR spectroscopies as a quantitative probe of local ion ordering in these compounds. Additionally, density functional electronic structure calculations on ordered and partially disordered Co${}_2$TiSn compounds have been carried out at a number of different levels of theory in order to simultaneously understand how the particular choice of DFT scheme as well as disorder affect the computed magnetization. Our studies suggest that a sample which seems well-ordered by X-ray diffraction and magnetization measurements can possess up to 10% of antisite (Co/Ti) disordering. Computations similarly suggest that even 12.5% antisite Co/Ti disorder does not destroy the half-metallic character of this material. However, the use of an appropriate level of non-local DFT is crucial.

11 pages and 5 figures

References in corpus (1)

• Electronic structure and spectroscopy of the quaternary Heusler alloy Co${}_2$Cr${}_{1-x}$Fe${}_x$Al