Magnetic and transport properties of tetragonal- or cubic-Heusler-type Co-substituted Mn-Ga epitaxial thin films

TL;DR

This study explores how Co substitution affects the structure, magnetism, and electrical resistivity of Mn-Ga epitaxial films, revealing a transition from tetragonal to cubic phases and increased resistivity with Co content.

Contribution

It provides detailed insights into the compositional dependence of structural and transport properties in Mn-Co-Ga thin films, highlighting the phase transition and disorder effects.

Findings

Structural transition from tetragonal to cubic with increasing Co

Maximum resistivity of 490 μΩcm at specific Co content

Lower saturation magnetization at high K_u values

Abstract

The composition dependence of the structural, magnetic, and transport properties of epitaxially grown Mn-Co-Ga films were investigated. The crystal structure was observed to change from tetragonal to cubic as the Co content was increased. In terms of the dependence of saturation magnetization on the Co content, relatively small value was obtained for the Mn$_{2.3}$Co$_{0.4}$Ga$_{1.3}$ film at a large {\it K}$_\textrm u$ value of 9.2 Merg/cm$^3$. Electrical resistivity of Mn-Co-Ga films was larger than that of pure Mn-Ga film. The maximum value of the resistivity was 490 $\mu\Omega$cm for Mn$_{2.2}$Co$_{0.6}$Ga$_{1.2}$ film. The high resistivity of Mn-Co-Ga might be due to the presence of localized electron states in the films due to chemical disordering caused by the Co substitution.