Current induced electromechanical strain in thin antipolar Ag₂Se semiconductor

Electromechanical coupling permits energy conversion between electrical and elastic forms, with wide applications^1,2. This conversion is usually observed in dielectric materials as piezoelectricity and electrostriction^3-7. 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.