Half-metallic quaternary CrYCoX(X = Si, Ge, Sn, Pb) alloys: DFT calculations and Monte Carlo simulation

Quaternary Heusler alloys with high spin polarization and high Curie temperature, and lower Gilbert damping parameters have broad application prospects in spintronics field, which motivates us to design the alloys with above-mentioned properties. In the current manuscript, we systematically studied the electronic structure, magnetic properties and Gilbert damping parameters of quaternary Heusler alloys CrYCoX(X = Si, Ge, Sn, Pb). Electronic calculations show that the CrYCoX alloys are half-metallic ferrimagnets, and their integer total magnetic moments obey the Slater-Pauling rule: M-t=Z(t)-18 Origin of half-metallic gap is discussed by hybridization, occupation and distribution of electronic states. According to the Heisenberg model, we calculated the exchange coupling parameters of CrYCoX alloys, and find that the competition and cooperation between d - d exchange, super-exchange and RKKY exchange lead to the emergence of ferrimagnetic phase. Curie temperatures of CrYCoX alloys calculated by mean-field approximation and Monte Carlo simulation are significantly higher than room temperature. Finally, Gilbert damping parameters of CrYCoX alloys calculated by via linear response theory are localized in 0.0051 similar to 0.0136 at 300 K, indicating they have lower energy loss and higher response speed as microwave and spintronic materials. Our results show that the CrYCoX alloys are promising candidates in room microwave and spintronic devices.