Layer-resolved spin polarization in Sb overlayers on NiMnSb

Authors

Ralph Skomski, University of Nebraska-LincolnFollow
T. Komesu, University of Nebraska-LincolnFollow
C.N. Borca, University of Nebraska-Lincoln
H.-K. Jeong, University of Nebraska-LincolnFollow
Peter A. Dowben, University of Nebraska-LincolnFollow
D. Ristoiu, CNRS, Laboratoire Louis Ne´el, France
J.P. Nozie´res, CNRS, Laboratoire Louis Ne´el, France

Date of this Version

June 2001

Comments

Published J. Appl. Phys. 89 (2001) 7275-7278. Permission to use.

Abstract

The magnetism of antimony overlayers on a ferromagnetic substrate is investigated by spin-polarized inverse photoemission and explained in terms of a spin-dependent envelope-function approximation (SDEFA). The atomic structure of the films, which were deposited by sputtering Sb onto a NiMnSb(001) substrate, is characterized by a unique combination of three features: (i) NiMnSb is a highly spin-polarized semi-Heusler alloy predicted to be halfmetallic, (ii) antimony is a semimetal, exhibiting a band structure reminiscent of indirect-gap semiconductors, and (iii) the small lattice mismatch ensures a well-controlled interface. Combined x-ray absorption spectroscopy and spin-polarized inverse photoemission yield a layer-resolved spin polarization decaying on a length scale of the order of 1 nm. The unusual range of the spin polarization in the paramagnetic overlayer is explained by considering the alloy–antimony interface as a spin-dependent perturbation potential and taking into account the low effective masses of the Sb conduction electrons (only about 0.1 for both electrons and holes). © 2001 American Institute of Physics. [DOI: 10.1063/1.1357849]