Magnetic phase transition and spin-phonon coupling effect of antiferromagnetic NiO flakes probed by Raman spectroscopy

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 Ne<acute accent>el 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 twodimensional NiO flake to spintronics and are expected to play an important role in the spintronics.