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

We report on the coherent phonon spectroscopy of polymorphic MoTe2 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 MoTe2 was observed. The use of higher photon-energy excitation, however, was found to suppress tellurium segregation. Typeset by REVTEX 1 ar X iv :2 20 1. 03 33 7v 1 [ co nd -m at .m tr lsc i] 1 0 Ja n 20 22