Electrical spectroscopy of the spin-wave dispersion and bistability in gallium-doped yttrium iron garnet

TL;DR

This study uses electrical spectroscopy to analyze spin-wave dispersion and bistability in gallium-doped yttrium iron garnet, revealing isotropic transport properties and nonlinear mode behavior in a low-magnetization magnetic insulator.

Contribution

It provides the first detailed electrical spectroscopy characterization of Ga:YIG's spin-wave dispersion and bistability, demonstrating its potential for spin-wave optics and information processing.

Findings

Determined magnetic anisotropy parameters from ferromagnetic resonance.

Measured exchange constant as 1.3(2)×10^{-12} J/m.

Observed spin-wave mode foldover at high drive power.

Abstract

Yttrium iron garnet (YIG) is a magnetic insulator with record-low damping, allowing spin-wave transport over macroscopic distances. Doping YIG with gallium ions greatly reduces the demagnetizing field and introduces a perpendicular magnetic anisotropy, which leads to an isotropic spin-wave dispersion that facilitates spin-wave optics and spin-wave steering. Here, we characterize the dispersion of a gallium-doped YIG (Ga:YIG) thin film using electrical spectroscopy. We determine the magnetic anisotropy parameters from the ferromagnetic resonance frequency and use propagating spin wave spectroscopy in the Damon-Eshbach configuration to detect the small spin-wave magnetic fields of this ultrathin weak magnet over a wide range of wavevectors, enabling the extraction of the exchange constant $\alpha=1.3(2)\times10^{-12}$ J/m. The frequencies of the spin waves shift with increasing drive power, which eventually leads to the foldover of the spin-wave modes. Our results shed light on isotropic spin-wave transport in Ga:YIG and highlight the potential of electrical spectroscopy to map out the dispersion and bistability of propagating spin waves in magnets with a low saturation magnetization.