THz Field-induced Spin Dynamics in Ferrimagnetic Iron Garnets

TL;DR

This paper demonstrates that THz magnetic field pulses can induce and analyze high-frequency spin dynamics in ferrimagnetic iron garnets, revealing exchange mode excitations and offering a new method for studying spin mechanisms.

Contribution

It introduces a novel approach using THz pulses to excite and analyze exchange mode spin dynamics in ferrimagnets, combining experimental data with numerical modeling.

Findings

THz pulses induce high-frequency magnetization dynamics.

Dynamics correspond to exchange mode excited by Zeeman interaction.

THz-pump IR-probe offers a new tool for spin studies.

Abstract

THz magnetization dynamics is excited in ferrimagnetic thulium iron garnet with a picosecond, single-cycle magnetic field pulse and seen as a high-frequency modulation of the magneto-optical Faraday effect. Data analysis combined with numerical modelling and evaluation of the effective Lagrangian allow us to conclude that the dynamics corresponds to the exchange mode excited by Zeeman interaction of the THz field with the antiferromagnetically coupled spins. We argue that THz-pump IR-probe experiments on ferrimagnets offer a unique tool for quantitative studies of dynamics and mechanisms to control antiferromagnetically coupled spins.