Laser-induced THz magnetization precession for a tetragonal Heusler-like nearly compensated ferrimagnet

TL;DR

This study investigates laser-induced magnetization dynamics in Mn$_3$Ge, revealing high-frequency precession modes and damping properties relevant for ultrafast spintronic applications.

Contribution

It reports the observation of THz-range FMR modes and analyzes the damping mechanisms in a tetragonal Heusler-like ferrimagnet, advancing understanding of ultrafast magnetic phenomena.

Findings

FMR mode frequency exceeds 0.5 THz

Effective damping constant is approximately 0.03

Effective Landau-Lifshitz constant is about 60 Mrad/s

Abstract

Laser-induced magnetization precessional dynamics was investigated in epitaxial films of Mn$_3$Ge, which is a tetragonal Heusler-like nearly compensated ferrimagnet. The ferromagnetic resonance (FMR) mode was observed, the precession frequency for which exceeded 0.5 THz and originated from the large magnetic anisotropy field of approximately 200 kOe for this ferrimagnet. The effective damping constant was approximately 0.03. The corresponding effective Landau-Lifshitz constant of approximately 60 Mrad/s and is comparable to those of the similar Mn-Ga materials. The physical mechanisms for the Gilbert damping and for the laser-induced excitation of the FMR mode were also discussed in terms of the spin-orbit-induced damping and the laser-induced ultrafast modulation of the magnetic anisotropy, respectively.