First Principle Materials Design of Half-Metallic Ferromagnetic Half-Heusler Alloys

We present a first principle study of the half-metallicity and ferromagnetism in half-Heusler alloys XYSi (X= Ni, Pd and Pt; Y= Cr and Mn). The equilibrium lattice constants are predicted by means of the ultrasoft pseudo-potential method. The electronic structure and magnetic exchange interaction of various alloys are investigated within KKR-LSDA. The Curie temperature is predicted by using the Monte Carlo simulation, the random phase and mean field approximations, as well. The role of elements X, Y components and influence of the lattice parameters in stabilizing half-metallicity and ferromagnetism are discussed. Except PdMnSi, alloys are half-metallic at equilibrium lattice constant. The Curie temperatures of 634 K, 785 K, and 1076 K for NiCrSi, PtMnSi and NiMnSi, respectively, are predicted by Monte Carlo simulation. The structural stability of C1_b is also considered.