Effect of atomic disorder on electronic, magnetic and electron-transport properties of Ti2MnAl

Abstract We report the combined computational and experimental study on the effect of atomic disorder on electronic, magnetic, and electron-transport properties of Ti2MnAl Heusler alloy. Ti2MnAl is predicted to exhibit spin-gapless semiconducting behavior in the inverted cubic crystal structure, while the regular cubic structure is essentially non-spin-polarized and non-magnetic. Here, we analyze three types of atomic disorder, namely, A2, B2, and D03, which are commonly observed in Heusler alloys. Our first-principles calculations indicate that all three types of disorder have a relatively small effect on a non-spin-polarized nature of Ti2MnAl in the regular cubic crystal (prototype Cu2MnAl) structure. At the same time, the inverted cubic phase (prototype Hg2TiCu) retains a significant degree of spin-polarization in A2 and B2 disordered structures. In particular, A2 and B2 types of disorder of the inverted cubic phase result in a spin-polarization of about 50% and 74%, respectively. The D03 disordered inverted phase has a significantly smaller spin-polarization of less than 10%. All considered structures align ferrimagnetically, except the B2-disordered and non-disordered regular cubic phases, which are non-magnetic. Our experimental results are consistent with the predicted properties of Ti2MnAl with partial A2 and B2 disorder types. While atomic disorder in a considered system should be minimized or avoided for practical implementations, its type may play a decisive role for potential applications in spin-based electronics.