Electronic structures, magnetic properties and lattice strain effects of quaternary Heusler alloys RuMnCrZ (Z  =  P, As, Sb)

Self-consistent first-principles calculations with the generalized gradient approximation are employed to study the electronic structures, magnetic properties, effects of uniform strain and tetragonal distortion on RuMnCrZ(Z  =  P, As and Sb). It is found that they are all half-metallic ferrimagnets. Calculations show that the total magnetic moments of RuMnCrZ(Z  =  P, As and Sb) are in agreement with the Slater–Pauling 24 electron-rule. The effects of uniform strain and tetragonal distortion are studied for RuMnCrSb. For uniform strain, large spin-down band gaps are observed between  −4% and 0 and E _F is located within the gap in the range of  −2% to 0. Furthermore, the total magnetic moment is 2 from  −4% to 0 uniform strain, and the spin polarization P of 100% is observed in the range of  −2% to 0, which indicates that the perfect half-metallicity of RuMnCrSb is maintained within the range. For tetragonal distortion, the spin-down band gaps exist for a large range of distortion:  −8% distortion 6% and the Fermi level is always within the gap for this range. 100% P and the total magnetic moment of 2 are maintained within the range of  −6% to  +5%. It is concluded that the perfect half-metallicity of RuMnCrSb appears in the range of  −6% to  +5% tetragonal distortion. The half-metallicity is more stable in the case of tetragonal distortion. (paper)