Local structure of highly spin polarized Heusler compounds revealed by nuclear magnetic resonance spectroscopy

A key tool in the rational design of spin polarised materials is the pre- cise control of the relationships between structure and physical properties, such as between structure and magnetism or transport properties. Thus, a sophisticated and comprehensive characterisation is required in order to understand, tune and con- trol the macroscopic properties of spin polarised materials towards optimised per- formance in spintronics devices. Nuclear magnetic resonance spectroscopy (NMR) probes the local environments of the active nuclei and is based on the interaction of the spin of a nucleus with the effective field present at the nucleus. The local character of NMR arises from local contributions to the hyperfine field, namely the transferred field which depends on the nearest neighbour atoms and their mag- netic moments. This enables NMR to study structural properties of bulk samples as well as of thin films of spin polarised materials. Recent results confirmed that NMR is a very suitable tool to reveal structural contributions and foreign phases in spin polarised materials which are very difficult to detect with other methods like, e.g., conventional X-ray diffraction. In this chapter, recent NMR studies of the lo- cal structure of various Heusler compounds will be presented and the impact of the NMR results on their potential for spintronics will be discussed.