Ultrafast dynamics of the low frequency shear mode in $1{\mathrm{T}}^{\prime }-\mathrm{MoT}{\mathrm{e}}_2$

Abstract

We report on the dynamics of coherent phonons in semimetal 1T'-MoTe2 using femtosecond pump-probe spectroscopy. On an ultrafast sub-picosecond time scale at room temperature, a low frequency and long-lifetime shear phonon mode was observed at 0.39 THz, which was previously reported in the form of a characteristic phonon only in the low temperature Td-MoTe2 phase. Unlike the other optical phonon modes, the shear phonon mode was found to strongly couple with photoexcited carriers. Moreover, the amplitude of the shear mode surprisingly decreased with increasing excitation density, a phenomenon which can be attributed to be a consequence of the lattice temperature rising after excitation. These results provide useful physical information on ultrafast lattice symmetry switching between the normal semimetal 1T' and the lattice inversion symmetry breaking Type-II Weyl semimetal Td phases.

arXiv comment5 pages, 4 figures, accepted for Applied Physics Letters

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• Ultrafast scattering dynamics of coherent phonons in Bi${}_{1-x}$Sb${}_x$ in the Weyl semimetal phase
• Role of interlayer shear phonons on lattice symmetry switching in the transition metal dichalcogenide WTe${}_2$
• Large change of interlayer vibrational coupling with stacking in Mo${}_{1-x}$W${}_x$Te${}_2$
• Giant Shear Displacement by Light-Induced Raman Force in Bilayer Graphene
• Light-induced shear phonon splitting and instability in bilayer graphene
• Research on topological materials using ultrafast spectroscopy
• Ultrafast dynamics of coherent phonons and phonon-polaritons in lithium niobate crystals
• Light-Induced Transient Polarization Reversal in Rhombohedrally Stacked Bilayer Transition Metal Dichalcogenides via an Electronic Mechanism
• Coherent Phonon-Driven Band Renormalizations in 1T${}^{\prime }$-MoTe${}_2$