Ab initio prediction of ferrimagnetism, exchange interactions and Curie temperatures in Mn2TiZ Heusler compounds

TL;DR

This study uses ab initio calculations to analyze the magnetic properties, exchange interactions, and Curie temperatures of Mn2TiZ Heusler compounds, identifying promising candidates for spintronic devices.

Contribution

The paper provides a comprehensive ab initio analysis of Mn2TiZ Heusler compounds, revealing their magnetic behavior, exchange interactions, and potential for spintronic applications, which was not previously detailed.

Findings

Many compounds exhibit over 90% spin polarization.

Curie temperatures are above room temperature.

The magnetic moment follows the Slater-Pauling rule.

Abstract

The Heusler compounds Mn$_2$TiZ (Z = Al, Ga, In, Si, Ge, Sn, P, As, Sb) are of large interest due to their potential ferrimagnetic properties and high spin polarization. Here, we present calculations of the structural and magnetic properties of these materials. Their magnetic moment follows the Slater-Pauling rule $m = N_V - 24$. None of them is actually a perfect half-metallic ferrimagnet, but some exhibit more than 90% spin polarization and Curie temperatures well above room temperature. The exchange interactions are complex, direct and indirect exchange contributions are identified. The Curie temperature scales with the total magnetic moment, and it has a positive pressure dependence. The role of the Z element is investigated: it influences the properties of the compounds mainly via its valence electron number and its atomic radius, which determines the lattice parameter. Based on these results, Mn$_2$TiSi, Mn$_2$TiGe, and Mn$_2$TiSn are proposed as candidates for spintronic applications.