Surface properties of the half-metallicity in ternary compounds: Fe(Cr,Mn)As based on different correlations

Previous studies show that FeCrAs and FeMnAs half-Heusler compounds exhibit half-metallic properties. Based on the generalised gradient approximation (GGA) local density approximation (LDA), and +U correction, we discuss the electronic and magnetic properties for the bulk and (0 0 1) surface of Fe(Cr, Mn)As half-Heusler compounds with a Clb structure, based on the first-principle computation. We found that the lattice constant significantly depends on the exchange-correlation interaction, and both alloys demonstrate the half-metallic property with full-spin polarisation with high Curie temperature. In (0 0 1) FeCrAs and FeMnAs surfaces, we noted that the half-metallicity, spin polarisation, and magnetic moment were dependent on the exchange correlation. For Cr-As, we obtained a higher spin polarisation with LDA and GGA + U, with values of 94% and 95%, respectively, and FeCrAs and FeMnAs with LDA + U achieved a value of 94%. In the Mn-As terminated surface, we observed that half-metallicity was confirmed with a spin polarisation equal to 100% with GGA + U only, and for FeCrAs and FeMnAs, a value of 43% with LDA was achieved. These calculations indicate that the effect of correlation is sensitive for the electronic and magnetic properties of both compounds.