Despite a plethora of materials suggested for spintronic applications, a new class of materials has emerged, namely spin gapless semiconductors (SGS), which offers potentially more advantageous properties than existing ones. These magnetic semiconductors exhibit a finite band gap for one spin channel and a closed gap for the other. Here, supported by electronic-structure calculations, we report evidence of SGS behavior in equiatomic quaternary CoFeCrGa, having a cubic Heusler (prototype LiMgPdSn) structure but exhibiting chemical disorder (${\mathrm{DO}}_3$ structure). CoFeCrGa is found to transform from SGS to half-metallic phase under pressure, which is attributed to unique electronic-structure features. The saturation magnetization $\left(M_S\right)$ obtained at $8\mathrm{K}$ agrees with the Slater-Pauling rule and the Curie temperature $\left(T_C\right)$ is found to exceed $400\mathrm{K}$. Carrier concentration (up to $250\mathrm{K}$) and electrical conductivity are observed to be nearly temperature independent, prerequisites for SGS. The anomalous Hall coefficient is estimated to be $185\mathrm{S}/\mathrm{cm}$ at $5\mathrm{K}$. Considering the SGS properties and high $T_C$, this material appears to be promising for spintronic applications.

• Received 1 March 2015
• Revised 23 April 2015

DOI:https://doi.org/10.1103/PhysRevB.92.045201