Investigations on stability, Gilbert damping, electronic and magnetic properties along with Curie temperature for quaternary Heusler alloys CrTiCo[formula omitted

Abstract

In the current manuscript, we systematically investigated the stability, Gilbert damping parameters, electronic and magnetic properties, exchange interactions and Curie temperatures of quaternary Heusler alloys CrTiCoZ (Z=Al, Ga, In). Stability calculations show that the CrTiCoZ alloys meet mechanical, thermodynamic and dynamic stabilities. Gilbert damping parameters of CrTiCoZ alloys calculated via linear response theory are localized in 0.006∼0.054 at 300 K, indicating they have lower energy loss and higher response speed as microwave and spintronic materials. Electronic calculations indicate that the CrTiCoIn is half-metallic ferrimagnet, and its integer total magnetic moment obeys the Slater–Pauling rule: Mt=Zt-18, while the CrTiCoAl and CrTiCoGa are nearly half-metals. After applying the GGA+U and HSE06 methods, it was found that the CrTiCoAl and CrTiCoGa alloys exhibit half-metallic properties. However, the CrTiCoIn alloy loses its half-metallicity. 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 CrTiCoZ alloys, and found that the competition and cooperation between d-d exchange and RKKY exchange lead to the emergence of ferrimagnetic phase. Finally, we estimated the Curie temperatures of CrTiCoZ alloys by using mean-field approximation and Monte Carlo simulation, the calculated Curie temperatures are noticeably higher than room temperature. High spin polarization and Curie temperature as well as lower Gilbert damping parameters make the CrTiCoZ alloys as a promising material for microwave or spintronics applications.