# Current induced electromechanical strain in thin antipolar Ag2Se semiconductor

## TL;DR

Electric current in thin Ag2Se semiconductor causes a large electromechanical strain through dipole changes and phase transition.

## Contribution

Discovery of giant electromechanical strain in Ag2Se via current-induced dipole alteration and phase transition.

## Key findings

- Electric current triggers a 6.7% local strain in Ag2Se through dipole alteration and phase transition.
- Strain is accompanied by changes in electroelastic deformation and electric conductivity.
- Both thermal and athermal effects contribute to the electromechanical coupling.

## Abstract

Electromechanical coupling permits energy conversion between electrical and elastic forms, with wide applications1,2. This conversion is usually observed in dielectric materials as piezoelectricity and electrostriction3–7. Electromechanical coupling response has also been observed in semiconductors8, however, the mechanism in semiconductors with a small bandgap remains contentious. Here we present a breakthrough discovery of a giant electromechanical strain triggered by the electric current in thin antipolar Ag2Se semiconductor. This phenomenon is made possible by the alteration of dipoles at a low current density (step I), followed by a phase transition under a moderate current density (step II), leading to a local strain of 6.7% measured by in-situ transmission electron microscopy. Our finding demonstrates that electric current has both thermal and athermal effect (e.g. alteration of dipoles and interaction of dipole vortices with the electric current). This strain allows for the concurrent control of electroelastic deformation and electric conductivity.

By an alteration of dipoles and a phase transition, the authors find a giant electromechanical strain triggered by the electric current in thin antipolar Ag2Se semiconductor. The strain has inherent flexibility and conductivity.