Gilbert Damping and Curie Temperature for Half-Metallic Equiatomic Quaternary Heusler Alloys Crycoz

Using first-principles calculations, we study the structural stability, Gilbert damping parameters, electronic structure, exchange interaction and Curie temperature of CrYCoZ (Z=Al, Ga, In, Tl) alloys. Stability is estimated from the perspective of thermodynamics, dynamics and mechanics. Gilbert damping parameters are calculated by using the linear response formalism, and the values 0.6∼4.1×10−3 are observed at room temperature. Electronic calculations show that the CrYCoZ alloys are half-metallic ferrimagnets, and their total magnetic moments follow the Slater-Pauling rule Mt=Zt-18. The origin of half-metallic gap is discussed by the hybridization, distribution and occupation of electronic states as well as the charge transfer. Based on the Heisenberg model, we calculate the exchange interactions between atomic components, and analyze the competition and collaboration between d-d exchange, super-exchange and RKKY exchange, finally offer the dominant mechanism of appearance of ferrimagnetic phase. Furthermore, we calculate the Curie temperature of CrYCoZ alloys by using mean-field approximation and Monte Carlo simulation, the evaluated Curie temperatures are evidently higher than room temperature. Overall, the CrYCoZ alloys can be considered as a promising candidates in spintronic application