Temperature-dependent anisotropy variation in quasi-two-dimensional ferromagnetic Cr5Te8

The quasi-two-dimensional ferromagnet Cr5Te8 is a promising material for spintronic devices due to its near-room-temperature Curie temperature (TC), strong magnetic anisotropy, and easily controllable properties. In this study, the anisotropic magnetization of trigonal (T-) Cr5Te8 single crystals is investigated. Our magnetization study reveals that a ferromagnetic transition occurs when the magnetic field is aligned parallel to the c-axis (H//c), while an antiferromagnetic transition appears for H//ab, with a strong perpendicular anisotropy in the ground state. However, electron spin resonance (ESR) spectroscopy indicates that the direction of the easy-axis changes from the c-axis to the ab-plane at TV∼ 190 K as the temperature increases. Furthermore, angle-dependent ESR spectra demonstrate a characteristic of two-dimensional magnetism in the bulk Cr5Te8 single crystal. It is suggested that the temperature-dependent variation in anisotropy is caused by changes in lattice structure through the tuning of the dominant direct-exchange between the intralayers and the super-exchange within the interlayers. The temperature- and field-dependent microwave responses of T-Cr5Te8 are advantageous for the application of this material as a microwave-based spintronic device.