Effect of surfaces and interfaces on the electronic, magnetic and gap-related properties of the half-metal Co$_2$MnSn

TL;DR

This study uses advanced electronic structure calculations to analyze how surfaces and interfaces affect the half-metallic, magnetic, and electronic properties of Co$_2$MnSn, revealing that interfaces can destroy its half-metallicity and impact spin-polarization.

Contribution

It provides detailed insights into the surface and interface effects on the electronic and magnetic properties of Co$_2$MnSn, highlighting the loss of half-metallicity at interfaces with metals and semiconductors.

Findings

Bulk Co$_2$MnSn is a half-metallic ferromagnet with a 5 μB magnetic moment.

(001) surfaces break half-metallicity due to surface states at the Fermi level.

Interfaces with V and InAs lose half-metallicity, affecting spin-polarization.

Abstract

We present state-of-the-art electronic structure calculations for the Co$_2$MnSn full-Heusler alloy. We show that in its bulk form it is a half-metallic ferromagnet with the Fermi level being located within a tiny gap of the minority-spin density of states. Moreover the alloy shows the Slater-Pauling behavior with a total spin magnetic moment in the unit cell of 5 $\mu_B$. In the case of the (001) surfaces, the broken bonds at the surface form a minority band pinned exactly at the Fermi level destroying the half-metallicity. Our calculations reveal that both the interfaces with the non-magnetic metal V and the semiconductor InAs are no more half-metallic due to the different environment of the atoms of the half-metal at the interface. These interface states although localized only at the first few interface layers can become conducting when coupled to defect states and kill the spin-polarization of the current injected from the half-metal into the semiconductor or the non-magnetic metallic spacer.