Structural and magnetic properties of the (001) and (111) surfaces of the half-metal NiMnSb

TL;DR

This study uses first-principles calculations to analyze how the (001) and (111) surfaces of NiMnSb, a half-metallic Heusler alloy, lose their bulk spin-polarization, with relaxations partially restoring it especially on the (111) surfaces.

Contribution

It provides a detailed first-principles analysis of surface terminations and relaxations affecting spin-polarization in NiMnSb surfaces, highlighting differences between (001) and (111) orientations.

Findings

Surfaces generally lose half-metallicity and spin-polarization.

(111) surfaces exhibit more pronounced loss of half-metallicity.

Surface relaxations can partially restore spin-polarization.

Abstract

Using the full potential linearised augmented planewave method we study the electronic and magnetic properties of the (001) and (111) surfaces of the half-metallic Heusler alloy NiMnSb from first-principles. We take into account all possible surface terminations including relaxations of these surfaces. Special attention is paid to the spin-polarization at the Fermi level which governs the spin-injection from such a metal into a semiconductor. In general, these surfaces lose the half-metallic character of the bulk NiMnSb, but for the (111) surfaces this loss is more pronounced. Although structural optimization does not change these features qualitatively, specifically for the (111) surfaces relaxations can compensate much of the spin-polarization at the Fermi surface that has been lost upon formation of the surface.