A LANDAU-GINZBURG DESCRIPTION OF Sb OVERLAYERS

Authors

Ralph Skomski, University of Nebraska-LincolnFollow
T. Komesu, University of Nebraska-LincolnFollow
H.-K. Jeong, University of Nebraska-LincolnFollow
C.N. Borca, University of Nebraska-Lincoln
Peter A. Dowben, University of Nebraska-LincolnFollow
D. Ristoiu, CNRS, Laboratoire Louis Néel, Avenue des Martyrs BP 166, 38042 Grenoble, CEDEX 09, France.
J.P. Nozieres, CNRS, Laboratoire Louis Néel, Avenue des Martyrs BP 166, 38042 Grenoble, CEDEX 09, France.

Date of this Version

May 2001

Comments

Published in Mat. Res. Soc. Symp. Proc. Vol. 674. © 2001 Materials Research Society. Permission to use.

Abstract

The spin polarization of Sb overlayers on the semi-Heusler alloy NiMnSb is investigated in terms of the Landau-Ginzburg approach. The half-metallic semi-Heusler alloy NiMnSb acts as a ferromagnetic perturbation and induces a spin polarization in the semimetallic Sb overlayer. Using a Gaussian approximation, the propagation of the spin perturbation in the overlayer is calculated. The results are compared with spin-polarized inverse photoemission spectroscopy (SPIPES) results and with recent spin-dependent envelope-function approximation (SDEFA) predictions. The Landau-Ginzburg parameters are both band-structure and temperature dependent, and it is argued that thermal spin excitations lead to an injection depth decreasing as 1//T law at high temperatures.