paper

Nonequilibrium carrier and phonon dynamics in the ferrimagnetic semiconductor Mn $_{3}$ Si $_{2}$ Te $_{6}$

arXiv:2405.11737 · doi:10.1103/PhysRevB.109.174309

Abstract

We investigate the ultrafast carrier and phonon dynamics in the ferrimagnetic semiconductor Mn $_{3}$ Si $_{2}$ Te $_{6}$ using time-resolved optical pump-probe spectroscopy. Our results reveal that the electron-phonon thermalization process with a subpicosecond timescale is prolonged by the hot-phonon bottleneck effect. We identify the subsequent relaxation processes associated with two non-radiative recombination mechanisms, i.e., phonon-assisted electron-hole recombination and defect-related Shockley-Read-Hall recombination. Temperature-dependent measurements indicate that all three relaxation components show large variation around 175 and 78 K, which is related to the initiation of spin fluctuation and ferrimagnetic order in Mn $_{3}$ Si $_{2}$ Te $_{6}$ . In addition, two pronounced coherent optical phonons are observed, in which the phonon with a frequency of 3.7 THz is attributed to the $A_{1 g}$ mode of Te precipitates. Applying the strain pulse propagation model to the coherent acoustic phonons yields a penetration depth of 506 nm and a sound speed of 2.42 km/s in Mn $_{3}$ Si $_{2}$ Te $_{6}$ . Our results develop understanding of the nonequilibrium properties of the ferrimagnetic semiconductor Mn $_{3}$ Si $_{2}$ Te $_{6}$ , and also shed light on its potential applications in optoelectronic and spintronic devices.

7 pages, 6 figures

Nonequilibrium carrier and phonon dynamics in the ferrimagnetic semiconductor Mn3​Si2​Te6​

Abstract

Nonequilibrium carrier and phonon dynamics in the ferrimagnetic semiconductor Mn $_{3}$ Si $_{2}$ Te $_{6}$