DFT+U, TB-mBJ, and hybrid approaches: investigating electronic topology and magnetic properties in Sn-doped Co2TiGa

Abstract

Cobalt-based Heusler compounds represent a new class of Heusler alloys which absorbed a lot of attention due to their performance in spintronics and magnetic devices. in this paper we have studied and analyzed the electronic structure and half-metallic ferromagnetic properties of Co2TiGa and Sn substituted at Ga site via the density functional theory (DFT) based first principle calculations with GGA-PBE, PBE+U, TB-MBJ exchange correlation potential and HSE06 approach. The band structure topology indicates that the parent ternary Heusler compound is ferromagnetic half-metallic with a half-metallic gap (band gap in the minority channel). The gap is increased according to the correction made on the exchange correlation potential. The half-metallic ferromagnetic behavior is confirmed by the total magnetizations which are very close to integrals Bohr magneton (1 μ B and 3μ B for Co2TiGa and Mn2TiGa0.5Sn0.5, respectively). The origin of half-metallic ferromagnetic is the p − d exchange and double-exchange interaction between the Co d-t2g states and neighboring Ti atom. The substitution effect on half-metallicity for Co2TiGa0.5 Sn0.5 was investigated in the tetragonal structure. The spontaneous magnetization obeyed the Slater-Pauling rule, indicating the Co2TiGa0.5 Sn0.5 is half-metal with 100% spin polarization.