2024/09/23 by Shogo Yamashita, Akimasa Sakuma, Yamashita, Shogo +3
Engineering · Materials Science · #FOS: Physical sciences #Heusler alloys: electronic and magnetic properties #Intermetallics and Advanced Alloy Properties #MXene and MAX Phase Materials #Materials Science (cond-mat.mtrl-sci)
paper · pdf · doi:10.48550/arxiv.2409.14802
openalex publication_date 2024/09/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We performed first-principles calculations at finite temperatures to investigate the temperature dependence of the magnetic properties, such as exchange stiffness constants and Curie temperatures, of Co2MnZ (Z= Si, Al) assuming L21 and B2 structures. In L21 structures, we confirmed a relatively high Curie temperature for Co2MnAl, compatible with that of Co2MnSi; however, its exchange stiffness constant and single site magnetic excitation energy at zero temperature are much smaller than those of Co2MnSi. This might indicate that the Curie temperature of itinerant magnets cannot be determined by the exchange interaction at zero temperature. We also investigated the temperature dependence of the exchange stiffness constants of both alloys, and we found robustness in the temperature dependence of the exchange stiffness constant for Co2MnAl, assuming an L21 structure. This might lead to a high Curie temperature, contrary to the small exchange stiffness constant. Finally, we examined the temperature dependence of the electronic structure to investigate the origin of the behavior of the exchange stiffness constant at finite temperatures. We confirmed that the spin polarization at chemical potential effectively increases with an increasing temperature due to the altered electronic structure induced by the spin disorder. This might contribute to the robustness of the exchange stiffness constant at finite temperatures. Our results might indicate that renomarization of the electronic structure due to spin disorder at finite temperature influences the exchange interactions of Co2MnAl.