ELECTRONIC, MAGNETIC AND ELASTIC PROPERTIES OF NEW HALF-HEUSLER COMPOUNDS XBAGA(X=LI, NA, KANDRB)

The structural, half-metallic and elastic properties of the hypothetical half-Heusler compounds XBaGa (X=Li, Na, K, and Rb) were investigated using first-principles calculations within the generalized gradient approximation (GGA) and GGA+mbj based on density function theory (DFT). The absence of the transition-metal atoms makes these compounds important model systems for the study of origin and properties of half-metallic ferromagnetism of sp electron systems. It is shown that for all the compounds the ferromagnetic state is favorable than the non-magnetic state. 'It is also found that these compounds i.e.  KBaGa and RbBaGa   exhibit half metallic ferromagnetic properties with an integer magnetic moment of 2 μB per formula unit at their equilibrium lattice constants. The magnetic moment mainly originates from the spin polarization of p-like states of anion and partial involvement of cation d-like states (Ba). The individual elastic constants, shear modulus, Young's moduli, ratio B/G and the Poisson's ratio were also calculated. The compounds are ductile based on the ratio B/G, they may inherently be the least brittle materials.