Photo-induced Tellurium segregation in $\mathrm{MoTe_2}$

TL;DR

This study uses femtosecond laser spectroscopy to explore how high-density laser excitation affects structural phases and tellurium segregation in MoTe2, revealing segregation without phase change and suppression with higher photon energy.

Contribution

It demonstrates that femtosecond laser excitation induces tellurium segregation in MoTe2 without causing phase transitions, and higher photon energy can suppress this segregation.

Findings

Tellurium segregation occurs under femtosecond laser excitation.

No structural phase transition was observed despite segregation.

Higher photon energy suppresses tellurium segregation.

Abstract

We report on the coherent phonon spectroscopy of polymorphic $\mathrm{MoTe_2}$ single crystals using a femtosecond-pulsed laser to investigate the relationship between structural phase transitions and photo-thermal effects induced by high-density laser excitation. Even when a femtosecond pulsed laser was used, which generally induces fewer heat accumulation effects than the case for a CW laser, tellurium segregation was observed in coherent phonon spectra with increasing excitation density, while no structural phase transition among polymorphs of $\mathrm{MoTe_2}$ was observed. The use of higher photon-energy excitation, however, was found to suppress tellurium segregation.