Terahertz-driven magnetism dynamics in the orthoferrite DyFeO3

TL;DR

This study investigates how terahertz pulses can excite and control magnetization dynamics in DyFeO3, revealing the dominant role of magnetic fields in coupling to magnon modes and expanding understanding of ultrafast magnetic phenomena.

Contribution

It demonstrates that terahertz magnetic fields primarily drive magnon excitations in DyFeO3, highlighting a new mechanism for ultrafast magnetic control in orthoferrites.

Findings

Both quasi-ferromagnetic and quasi-antiferromagnetic magnon modes are excited.

Terahertz magnetic field, not electro-optical susceptibility, mainly couples to magnon modes.

Multiple resonances, including other modes, are observed in time-resolved measurements.

Abstract

Terahertz driven magnetization dynamics are explored in the orthoferrite DyFeO3. A high-field, single cycle THz pulse is used to excite magnon modes in the crystal together with other resonances. Both quasi-ferromagnetic and quasi-antiferromagnetic magnon modes are excited and appear in time-resolved measurements of the Faraday rotation. Other modes are also observed in the measurements of the time-resolved linear birefringence. Analysis of the excitation process reveals that despite larger than expected electro-optical susceptibility it is mainly the THz magnetic field that couples to the quasi-ferromagnetic and quasi-antiferromagnetic magnon branches.