Spin polarization of the transport current at the free surface of bulk NiMnSb
نویسندگان
چکیده
The point contact Andreev reflection employing niobium tips was used to determine the degree of transport current spin polarization sPtd at the free surface of bulk NiMnSb at 4.2 K. The data was analyzed within the framework of a modified version of the Blonder, Tinkham, and Klapwijk formulism taking into account the two spin polarized channels in the ferromagnet and treating the interface as a planar delta function barrier of height Z between free electron materials. We find that the measured spin polarization is rather insensitive to different surface preparations and magnetic domain structure, and the maximal value of the Pt at Z=0 is 44%, consistent with recent calculations of the surface reconstruction of NiMnSb. Saturation magnetization of the samples was found to be 3.6 mB per formula unit indicative of a small amount of atomic disorder.
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