New Quaternary Half-Metallic Materials of the Z t − 28 Rule in LiMgPdSn-Type Heusler Alloys

This paper presents first-principles calculations with the full-potential linearized augmented plane-wave method to study a series of LiMgPdSn-type Heusler alloys. The chemical formula is XX′YZ, where X = Fe, Co, or Ni; X′ = Mn; Y = Cu or Zn; and Z = Si, Al, Ga, or Ge. Eight compounds are found to be half-metallic magnets and obey the Slater–Pauling rule with the total number of valence electrons (Z t) of 28. The half-metallic band gap in CoMnZnSi compounds reaches its maximum of 0.66 eV. CoMnCuGe and CoMnZnGa can be transformed from a quasi-half-metallic alloy to a half-metallic alloy by employing sufficient compression stress.