First principle computation of half metallicity and mechanical properties of a new series of half Heusler alloys KMnZ (Z = B, Si, Ge, As) for spintronics

Abstract

In the framework of density functional theory, the first principle calculations are performed to investigate various physical properties of new series of half Heusler alloys KMnZ (Z = B, Si, Ge, As) by using WIEN2k code. The results of structural parameters show that ferromagnetic state is more stable, with Type 3, configuration than the non-magnetic and antiferromagnetic states for all KMnZ (Z = B, Si, Ge, As) compounds. All considered alloys KMnZ (Z = B, Si, Ge, As) are completely spin polarized and show half-metallic character because of the presence of band gap (BG) in minority-spin channels. The calculated magnetic moments are 3 µB, 4 µB, and 5 µB for KMnB, KMnSi (Ge), and KMnAs, respectively. The values of minority BG for KMnB, KMnSi, KMnGe, and KMnAs are 0.60 eV, 0.85 eV, 1.00 eV, and 1.20 eV, respectively. The origin of their HM gaps is also examined in addition to density of states and band structures. The Curie temperature (TC), within mean field approximation, is also calculated. The calculations for elastic constants and other mechanical parameters are computed to check the mechanical stability which revealed that all other alloys are stable with ductile nature except KMnB. From the results of several physical properties, it can be envisaged that these materials can be used for spintronic devices.