We report on the nonlinear magnetization dynamics of a HoFeO3 crystal induced by a strong terahertz magnetic field resonantly enhanced with a split ring resonator and measured with magneto-optical Kerr effect microscopy. The terahertz magnetic field induces a large change (~40%) in the spontaneous magnetization. The frequency of the antiferromagnetic resonance decreases in proportion to the square of the magnetization change. A modified Landau-Lifshitz-Gilbert equation with a phenomenological nonlinear damping term quantitatively reproduced the nonlinear dynamics.
@article{arxiv.1601.06213,
title = {Nonlinear magnetization dynamics of antiferromagnetic spin resonance induced by intense terahertz magnetic field},
author = {Y Mukai and H Hirori and T Yamamoto and H Kageyama and K Tanaka},
journal= {arXiv preprint arXiv:1601.06213},
year = {2016}
}