The effect of strain on the thawing of the hidden state and other transitions in 1T-TaS2

TL;DR

This study explores how in-plane strain affects phase transition temperatures in 1T-TaS2 thin films, revealing opposite effects on different states and highlighting strain's influence on electronic phase transitions.

Contribution

It provides new insights into strain effects on phase transitions in 1T-TaS2, showing differential impacts on hidden and charge-density wave states.

Findings

Strain significantly lowers the hidden state transition temperature T_H.

Transition temperature T_{c2} is weakly affected by tensile strain.

Opposite strain effects observed compared to hydrostatic pressure.

Abstract

We investigate the effect of 2-dimensional (in-plane) strain on the critical transition temperature TH from the photoexcited hidden state in 1T-TaS$_2$ thin films on different substrates. We also measure the effect of in-plane strain on the transition temperature $T_{c2}$ between the nearly commensurate charge-density wave state and the commensurate state near 200 K. In each case, the strain is caused by the differential contraction of the sample and the substrate, and ranges from 0.5 % compressive strain (CaF$_2$) to 2 % tensile strain (sapphire). Strain appears to have an opposite effect on the H state and the NC-C state transitions. TH shows a large and negative strain coefficient of dT$_H$/de = - 8900+/-500 K, while $T_{c2}$ is not strongly affected by tensile strain and shows a positive coefficient for compressive strain, which is opposite to the effect observed for hydrostatic pressure.