Density functional study of the half-metallic ferromagnetism in Co-based Heusler alloys Co2MSn (M = Ti, Zr, Hf) using LSDA and GGA

► In Co2MSn (M = Ti, Zr, and Hf) LSDA and GGA act differently on the orbitals. ► LSDA and GGA results about their half-metallic estate differ. GGA are half-metallic. ► LSDA miscalculated the occupied and unoccupied Co d orbitals. ► The calculated magnetic moment also shows differences between the two functionals. ► The Co-Co hybridization is central to explain the half-metallic state in these alloys.