Strain Engineering of Correlated Charge-Ordered Phases in 1T-TaS2

TL;DR

This study demonstrates how uniaxial strain can reversibly control charge density wave phases in 1T-TaS2, enabling room-temperature, electrically-readable strain sensors through piezoresistive effects.

Contribution

It introduces a flexible platform for strain tuning of CDW phases in 1T-TaS2 and develops a novel, room-temperature strain sensor based on this material.

Findings

Strain affects the NC-IC phase transition threshold voltage.

Resistance change shows quadratic dependence on strain.

A programmable, room-temperature strain sensor is demonstrated.

Abstract

Strain engineering is a powerful strategy for controlling the structural and electronic properties of two-dimensional materials, particularly in systems hosting charge density wave (CDW) order. In this work, we apply uniaxial tensile and compressive strain to thin 1T-TaS2 flakes using a flexible, device-compatible platform, and systematically investigate the strain-dependent behavior of the nearly commensurate (NC) to incommensurate (IC) CDW phase transition. This transition is driven by Joule heating at room temperature. Electrical transport measurements reveal that both the switching threshold voltage and the resistance of the NC-CDW phase exhibit clear, reversible strain dependence. Furthermore, we identify a quadratic dependence between the strain-induced resistance change and the threshold voltage, confirming that piezoresistive modulation governs the strain-tunability of the phase transition. We demonstrate a room-temperature, electrically-readout strain and displacement sensor with threshold-like response in a programmable window. These results highlight the potential of 1T-TaS2 for on-chip sensing of strain and displacement.