Spin-phonon interaction in yttrium iron garnet
Kevin Olsson, Jeongheon Choe, Martin Rodriguez-Vega, Guru Khalsa, Nicole A. Benedek, Jiaming He, Bin Fang, Jianshi Zhou, Gregory A. Fiete, Xiaoqin Li
Abstract
Spin-phonon interaction is an important channel for spin and energy relaxation in magnetic insulators. Understanding this interaction is critical for developing magnetic insulator-based spintronic devices. Quantifying this interaction in yttrium iron garnet (YIG), one of the most extensively investigated magnetic insulators, remains challenging because of the large number of atoms in a unit cell. Here, we report temperature-dependent and polarization-resolved Raman measurements in a YIG bulk crystal. We first classify the phonon modes based on their symmetry. We then develop a modified mean-field theory and define a symmetry-adapted parameter to quantify spin-phonon interaction in a phonon-mode specific way in YIG. Based on this improved mean-field theory, we discover a positive correlation between the spin-phonon interaction strength and the phonon frequency.