Polycrystalline samples of the half-metallic ferromagnet Heusler compound Co2TiSn have been prepared and studied using bulk techniques (X-ray diffraction and magnetization) as well as local probes (119Sn M\"ossbauer spectroscopy and 59Co nuclear magnetic resonance spectroscopy) in order to determine how disorder affects half-metallic behavior and also, to establish the joint use of M\"ossbauer 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 Co2TiSn 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.
@article{arxiv.cond-mat/0609578,
title = {Electronic structure, magnetism, and disorder in the Heusler compound Co$_2$TiSn},
author = {Hem Chandra Kandpal and Vadim Ksenofontov and Benjamin Balke and Marek Wojcik and Ram Seshadri and Claudia Felser},
journal= {arXiv preprint arXiv:cond-mat/0609578},
year = {2007}
}