Experimental and Theoretical Study on the Possible Half-Metallic Behavior of Co2-Xvxfege Heusler Alloys

We present a combined theoretical and experimental study of quaternary Heusler alloys Co 2-x V x FeGe with 0 ≤ x ≤ 1 prepared by arc melting and annealing, arguing they are promising candidates for spintronics applications. Single phase microstructures are observed for V compositions from x = 0.25 to x = 0.625. Other V concentrations studied are multi-phased. All single phase samples exhibit a face centered cubic crystal structure with a lattice constant increasing linearly with V concentration. The low-temperature saturation magnetic moments agree fairly well with our theoretical results and also obey the Slater-Pauling rule of thumb for half-metals, a prerequisite for half metallicity. All alloys are observed to have high Curie temperatures that scale linearly with the saturation magnetic moment, allowing for applications at room temperature and above. Electrical transport measurements are performed to elucidate the electronic structure of the alloys. The temperature dependence of electrical resistivity is analyzed and discussed in the framework of the two current conduction model taking into account the existence of an energy gap in the electronic spectrum around the Fermi level of the spin down sub-band. Our ab initio calculations with the HSE-06 exchange correlation functional also predict half-metallic character in the alloys after V substitution. High mechanical hardness values are also observed.