Experimental and first-principles investigation on magnetic properties and electronic structure in half-metallic Mn-Co-V-Al Heusler alloy

We report a systematic experimental and theoretical study of half-metallic Heusler alloys Mn2V1_xCoxAl (x = 0, 0.25, 0.5, 0.75, 1). In this study, using the arc-melting method and optimizing annealing temperatures, we succeed to synthesize Mn2V1_xCoxAl (x = 0, 0.25, 0.5, 0.75, 1) alloys with evident L21 (or XA) order. A near compensated ferrimagnetic moment of 0.02 & mu;B/f.u. at 5 K is observed with the Co concentration of 0.5 which is consistent with the S-P rule. In addition, we systematacially investigate the effects of Co concentration on electronic structure of Heusler alloys Mn2V1_xCoxAl (x = 0, 0.25, 0.5, 0.75, 1) using first-principles calculations, and found that the half-metallic characteristic persists for all Co concentrations. In line with our experimental results, employing appropriate atomic site occupation, we obtained a full compensated ferrimagnetic moment of 0 & mu;B/f.u. for stoichiometric Mn2V0.5Co0.5Al alloy. In addition, the robustness of half-metallic properties for compensated ferrimagnet Mn2V0.5Co0.5Al with the variation of atomic disorder are investigated and the results indicate that the Mn-Al swapping weakly destroys the half-metallic properties and the compensated ferrimagnet Mn2V0.5Co0.5Al alloy maintains the high spin polarization under the effect of B2 disorder.