Strong half-metallic ferromagnetism and thermoelectric response in new half-Heusler RbCrX (X = Sb, As) alloys: first-principles calculations

This study uses the density functional theory method to accurately predict structural, electronic, magnetic, elastic, thermal and thermoelectric properties for two new half-Heusler RbCrSb and RbCrAs compounds. The exchange and correlation potential is treated by employing generalized gradient approximation of Perdew-Burke-Ernzerhof (GGA-PBE), Tran-Blaha-modified Becke-Johnson exchange potential (TB-mBJ) and PBE-GGA + U approaches, where U is the Hubbard on-site Coulomb interaction correction. Structural results reveal that RbCrSb and RbCrAs alloys are energetically stable in type 3 structure FM state. The negative formation and cohesive energies confirm the possibility of their experimental realization. Electronic and magnetic properties show that both compounds exhibit half-metallic character and integer magnetic moments of 4 mu B following the Slater-Pauling rule. Elastic calculations unveil that both compounds fulfill the mechanical stability criteria and are anisotropic and ductile in nature. The thermodynamic properties show that the selected materials can be employed under high pressures and high temperatures. Thermoelectric results suggest that RbCrX (with X = Sb, As) exhibits high figure of merit (ZT) values close to the unity at room temperature. Consequently, our new half-Heusler compounds RbCrSb and RbCrAs will be beneficial for thermoelectricity as well as for spintronic device applications.