CoMnCrGa: a novel ferromagnetic material with high spin-polarization for room temperature spintronics

Abstract

Here, we report the synthesis of a novel quaternary Heusler alloy CoMnCrGa and its structural, magnetic, transport and electronic properties using both experimental and theoretical methods. DFT calculations on an ordered crystal structure with specific atomic positions (Ga at 4a, Mn at 4b, Cr at 4c and Co at 4d) reveal a half-metallic ferromagnetic (HMF) ground state having a very high spin polarization of 96.1%. In this work we show that despite having a mix of Mn (4b) and Cr (4c) atoms, CoMnCrGa exhibits all the signatures of the HMF characteristic, viz., adherence to the Slater–Pauling (S–P) rule to isothermal saturation magnetization and the absence of magnon scattering in temperature dependent resistivity data. Given its high T_C (∼807 K), low magnetic moment and very high spin-polarization, the compound is a promising candidate for room temperature spintronics applications.