Optical spectroscopy and ultrafast pump-probe study of structural phase transition in 1T'-TaTe2

TL;DR

This study investigates the electronic and structural changes in 1T'-TaTe2 during its first-order phase transition at 170 K using optical spectroscopy and ultrafast pump-probe techniques, revealing a sudden band structure reconstruction.

Contribution

It provides new insights into the electronic structural evolution and rules out density-wave instability as the cause of the phase transition in 1T'-TaTe2.

Findings

Abrupt changes in optical spectra at transition temperature

Sudden reconstruction of the band structure

Phase transition is of first order, not density-wave type

Abstract

1T'-TaTe2 exhibits an intriguing first-order structural phase transition at around 170 K. Understanding the electronic structural properties is a crucial way to comprehend the origin of the structural phase transition. We performed a combined optical and ultrafast pump-probe study on the compound across the transition temperature. The phase transition leads to abrupt changes of both optical spectra and ultrafast electronic relaxation dynamics. The measurements revealed a sudden reconstruction of band structure. We elaborate that the phase transition is of the first order and can not be attributed to the conventional density-wave type instability. Our work is illuminating for understanding the origin of the structural phase transition.