Spin - Phonon Coupling in thin film NiO: UV and Visible Raman Spectroscopy Investigation*

Nickel oxide (NiO) is an antiferromagnetic insulator with a crystalline structure consisting of ferromagnetically aligned (111) planes. This material has recently attracted significant attention owing to proposals for spintronic applications in the THz frequency regime. Raman spectroscopy can provide valuable information on the phonon and magnon states in such materials, and can possibly shed light on specifics of the phonon – magnon interactions. Here, we report a comparative Raman spectroscopic investigation of (111)-oriented NiO single crystals and NiO(111) thin films under ultraviolet (UV) and visible laser excitations, and we compare the bulk results with thin film results to explore the dimension effect. The measurements were conducted in the backscattering configuration under the laser excitation wavelength of 325 nm (resonant) and 488 nm (non-resonant). M. M. Lacerda et al., APL. 110, 202406 (2017).