We present a systematic study of the polarization of the transport current from a variety of NiMnSb and Co2 MnSi thin films and bulk material using point contact Andreev reflection spectroscopy. The simple analysis suggests that the free surface polarization of NiMnSb is within error 10% lower than that of Co2 MnSi. In either material the measured polarization is rather insensitive to key physical and material properties. We use a two channel model to rule out the influence that stray magnetic field from the ferromagnet might have on the measurements presented. © 2006 American Institute of Physics.

We report a detailed study of surface and interface properties of pulsed-laser-deposited NiMnSb films on a Si(100) substrate as a function of film thickness. As the thickness of films is reduced below 35 nm, formation of a porous layer is observed. Porosity in this layer increases with decrease in NiMnSb film thickness. These morphological changes of the ultrathin films are reflected in the interesting transport and magnetic properties of these films. Compositional anomaly and surface and interface roughness are not the source of magnetic and transport properties of the films. © 2006 The American Physical Society.

We report on the electrical and magnetotransport properties of the contact formed between n -type degenerate InSb (100) substrates and polycrystalline NiMnSb thin films grown using pulsed laser deposition. Negative giant magnetoresistance is observed when the external magnetic field is oriented parallel to the in-plane current direction. We attribute the observed phenomenon to magnetic precipitates that are formed during the magnetic film deposition and are confined to a thin layer at the interface. The evidence for the formation of a thin interfacial layer is obtained through x-ray reflectivity measurements. © 2006 The American Physical Society.