Spin-polarized two-dimensional electron/hole gas at the interface of non-magnetic semiconducting half-Heusler compounds: Modified Slater-Pauling rule for half-metallicity at the interface

TL;DR

This study uses first-principles calculations to explore magnetic and electronic properties at interfaces of non-magnetic half-Heusler compounds, revealing spin-polarized 2DEG/2DHG formation and proposing a modified Slater-Pauling rule for half-metallicity.

Contribution

It introduces a modified Slater-Pauling rule for half-metallicity at interfaces of half-Heusler compounds and analyzes their magnetic and electronic properties.

Findings

Interfaces become metallic and magnetic with spin polarization.

Formation of 2DEG or 2DHG at the interfaces.

Proposal of a modified Slater-Pauling rule for half-metallicity.

Abstract

Half-Heusler compounds with 18 valence electrons per unit cell are well-known non-magnetic semiconductors. Employing first-principles electronic band structure calculations, we study the interface properties of the half-Heusler heterojunctions based on FeVSb, CoTiSb, CoVSn, and NiTiSn compounds, which belong to this category of materials. Our results show that several of these heterojunction interfaces become not only metallic but also magnetic. The emergence of spin-polarization is accompanied by the formation of two-dimensional electron gas (2DEG) or hole gas (2DHG) at the interface. We qualitatively discuss the origin of the spin polarization at the interfaces on the basis of the Stoner model. For the cases of magnetic interfaces where half-metallicity is also present, we propose a modified Slater-Pauling rule similar to the one for bulk half-metallic half-Heusler compounds. Additionally, we calculate exchange parameters, Curie temperatures and magnetic anisotropy energies for magnetic interfaces. Our study, combined with the recent experimental evidence for the presence of 2DEG at CoTiSb/NiTiSn heterojunctions might motivate future efforts and studies toward the experimental realization of devices using the proposed heterojunctions.