Spin-phonon interaction in yttrium iron garnet

Abstract

Spin-phonon interaction is an important channel for spin and energy\nrelaxation in magnetic insulators. Understanding this interaction is critical\nfor developing magnetic insulator-based spintronic devices. Quantifying this\ninteraction in yttrium iron garnet (YIG), one of the most extensively\ninvestigated magnetic insulators, remains challenging because of the large\nnumber of atoms in a unit cell. Here, we report temperature-dependent and\npolarization-resolved Raman measurements in a YIG bulk crystal. We first\nclassify the phonon modes based on their symmetry. We then develop a modified\nmean-field theory and define a symmetry-adapted parameter to quantify\nspin-phonon interaction in a phonon-mode specific way for the first time in\nYIG. Based on this improved mean-field theory, we discover a positive\ncorrelation between the spin-phonon interaction strength and the phonon\nfrequency.\n