Development of spin-gapless semiconductivity and half metallicity in Ti$_{\mathrm{2}}$MnAl by substitutions for Al*

In recent years, ever increasing interest in spin-based electronics has resulted in the search for a new class of materials that can provide a high degree of spin polarized electron transport. An ideal candidate would act like insulator for one spin channel and a conductor or semiconductor for the opposite spin channel (e.g., half metal (HM), spin-gapless semiconductor (SGS)). Here, we present the combined computational, theoretical, and experimental study of Ti$_{\mathrm{2}}$MnAl, a Heusler compound with potential application in the field of spintronics. We show that in the ground state this material is metallic, however it becomes a SGS when 50{\%} of Al is substituted with In (e.g., Ti$_{\mathrm{2}}$MnAl$_{\mathrm{0.5}}$In$_{\mathrm{0.5}})$, and a HM when 50{\%} of Al is substituted with Sn (e.g., Ti$_{\mathrm{2}}$MnAl$_{\mathrm{0.5}}$Sn$_{\mathrm{0.5}})$. Detailed study of the structural, electronic, and magnetic properties of these materials is presented.