Two-dimensional antiferromagnetic materials have attracted wide attention in both performance and application, which are of great significance for spin valves and next-generation magnetic random access memory devices. The spin-phonon coupling effect plays a crucial role in magnon dynamics. However, there is still a lack of research on the spin-phonon coupling effect of two-dimensional antiferromagnetic flakes. In this work, the magnetic phase transition and spin-phonon coupling effect of NiO flakes were studied by Raman spectroscopy. The magnetic phase transition temperature of the two-dimensional NiO flake is TN = 468 K. When the temperature is lower than Néel temperature, the abnormal shift of phonon peaks and the temperature dependence of 2 M peak prove the magnetic order characteristics of NiO flakes. The spin-phonon coupling constants of LO, 2TO and 2LO modes are 3.5, 5.5 and 10 cm-1, respectively, by using the abnormal hardening of the phonon scattering mode relative to the anharmonic effects. These results clearly demonstrate the significance of the two-dimensional NiO flake to spintronics and are expected to play an important role in the spintronics.
Keywords: 2D materials; Magnetic phase transition; NiO; Spin-phonon coupling.
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