CubicMn2GaThin Films: Crossing the Spin Gap with Ruthenium

Abstract

Cubic ${\mathrm{Mn}}_2\mathrm{Ga}$ films with the half-Heusler $C{1}_b$ structure are grown on V (001) epitaxial films. The phase is a soft ferrimagnet, with Curie temperature $T_C=225\text{K}$ and magnetization $M_s=280\text{kA}{\text{m}}^{-1}$, equivalent to $1.65{\mu }_B$ per formula. Adding ruthenium leads to an increase of $T_C$ up to 550 K in cubic ${\text{Mn}}_2{\text{Ru}}_x\text{Ga}$ films with $x=0.33$ and a collapse of the net magnetization. The anomalous Hall effect changes sign at $x=0.5$, where the sign of the magnetization changes and the magnetic easy direction flips from in plane to perpendicular to the film. The ${\text{Mn}}_2{\text{Ru}}_{0.5}\text{Ga}$ compound with a valence electron count of 21 is identified as a zero-moment ferrimagnet with high spin polarization, which shows evidence of half-metallicity. DOI: http://dx.doi.org/10.1103/PhysRevLett.112.027201 © 2014 American Physical Society