A new spin gapless semiconductor: equiatomic quaternary Heusler alloy CoFeCrGa

Spin gapless semiconductors (SGS) constitute a new class of magnetic semiconductors, which exhibit an open band gap for one spin band and a closed one for the other spin band. In this paper, we report the first experimental evidence of SGS behavior in CoFeCrGa quaternary Heusler alloy, which is supported by the first principle electronic structure calculations. The alloy is found to exist in cubic Heusler structure (prototype LiMgPdSn) with considerable amount of DO3 order. The saturation magnetization (MS) value obtained at 8 K is in good agreement with the Slater-Pauling rule and the Curie temperature is found to be more than 400 K. Nearly temperature-independent carrier concentration (up to 250 K) and electrical conductivity are observed, which are typical of SGS materials. The anomalous Hall coefficient is estimated to be 185 S/cm at 5 K. Considering the high Curie temperature and proposed SGS behavior, this material appears to be very promising for spintronic applications.