Nonlinear and Thermal Effects in the Absorption of Microwaves by Random Magnets

Abstract

Abstract We study the temperature dependence of the absorption of microwaves by random-anisotropy magnets. It is governed by strong metastability due to the broad distribution of energy barriers separating different spin configurations. At a low microwave power, when the heating is negligible, the spin dynamics is close to linear. It corresponds to the precession of ferromagnetically ordered regions that are in resonance with the microwave field. Previously we have shown (doi.org/10.1103/PhysRevB.103.214414) that in this regime a dielectric substance packed with random magnets would be a strong microwave absorber in a broad frequency range. Here we demonstrate that on increasing the power, heating and over barrier spin transitions come into play, resulting in the nonlinear behavior. At elevated temperatures the absorption of microwave power decreases dramatically, making the dielectric substance with random magnets transparent for the microwaves.

arXiv comment8 PR pages, 7 figures

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Cited by in corpus (7)

• Random Anisotropy Magnet at Finite Temperature
• Integral Absorption of Microwave Power by Random-Anisotropy Magnets
• Skyrmion Crystal in a Microwave Field
• Scaling of Static and Dynamical Properties of Random Anisotropy Magnets
• Energy minima and ordering in ferromagnets with quenched randomness
• Static and Microwave Properties of Amorphous Magnets Near Saturation
• Radar shielding experiments by composite bilayer magnetic systems