Light induced sub-picosecond topological phase transition in MoTe2

TL;DR

This paper demonstrates a sub-picosecond, light-induced topological phase transition in MoTe2, switching between Weyl semimetal and normal phases using ultrafast laser pulses, with potential for ultrafast topological devices.

Contribution

It reports the first observation of a photo-induced, sub-picosecond topological phase transition in MoTe2, combining ultrafast spectroscopy techniques.

Findings

Clear change in shear oscillation mode

Significant intensity loss of second harmonic generation

Potential for ultrafast topological switching

Abstract

Recent development of ultrashort laser pulses allows for optical control of structural and electronic properties of complex quantum materials. The layered transition metal dichalcogenide MoTe2, which can crystalize into several different structures with distinct topological and electronic properties, provides possibilities to control or switch between different phases. In this study we report a photo-induced sub-picosecond structural transition between the type-II Weyl semimetal phase and normal semimetal phase in bulk crystalline MoTe2 by using ultrafast pump-probe and time-resolved second harmonic generation spectroscopy. The phase transition is most clearly characterized by the dramatic change of the shear oscillation mode and the intensity loss of second harmonic generation. This work opens up new possibilities for ultrafast manipulation of the topological properties of solids, enabling potentially practical applications for topological switch device with ultrafast excitations.