Nontrivial temperature dependence of ferromagnetic resonance frequency for spin reorientation transitions

Abstract

We find unusual temperature dependence of the ferromagnetic resonance (FMR) frequency $f_{\mathrm{R}}$ for the spin-reorientation (SR) transition, in which the easy axis changes depending on temperature, observed in the Nd permanent magnet, Nd${}_2$Fe${}_{14}$B: $f_{\mathrm{R}}\sim 0$ below the SR transition temperature ($T_{\mathrm{R}}$), drastic increase of $f_{\mathrm{R}}$ around $T_{\mathrm{R}}$, and decrease from a peak at higher temperatures. It is nontrivial that the SR transition causes the unusual behavior of the FMR frequency in a wide temperature region. We show the mechanism of the temperature dependence by theoretical and computational analyses. We derive a general relation between $f_{\mathrm{R}}$ and magnetizations to help the understanding of the mechanism, and clarify that the fluctuation of the transverse magnetization is a key ingredient for the resonance in all temperature regions.

5 pages, 4 figures, supplemental material

References in corpus (1)

• Realization of the thermal equilibrium in inhomogeneous magnetic systems by the Landau-Lifshitz-Gilbert equation with stochastic noise, and its dynamical aspects