Current induced electromechanical strain in thin antipolar Ag₂Se semiconductor.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Semiconductor Physics

Background:

• Electromechanical coupling enables energy conversion between electrical and elastic forms, crucial for various applications.
• While observed in dielectrics (piezoelectricity, electrostriction), mechanisms in narrow-bandgap semiconductors are debated.
• Previous studies noted electromechanical coupling in semiconductors, but the underlying physics in small bandgap materials remained unclear.

Purpose of the Study:

• To investigate the electromechanical coupling phenomenon in thin antipolar silver selenide (Ag2Se) semiconductor.
• To elucidate the mechanism of giant electromechanical strain induced by electric current in Ag2Se.
• To demonstrate the potential for concurrent control of electroelastic deformation and electrical conductivity.

Main Methods:

• Utilized in-situ transmission electron microscopy to measure local strain.
• Applied controlled electric current densities to thin antipolar Ag2Se samples.
• Analyzed the effects of current density on material's dipoles and phase transitions.

Main Results:

• Observed a giant electromechanical strain of 6.7% in Ag2Se.
• Identified two distinct steps: dipole alteration at low current density and phase transition at moderate current density.
• Demonstrated that electric current exhibits both thermal and athermal effects, including dipole alteration and interaction with dipole vortices.

Conclusions:

• Discovered a novel giant electromechanical strain phenomenon in Ag2Se driven by electric current.
• Established that electric current can induce significant deformation through dipole alteration and phase transitions.
• Showcased the potential of this phenomenon for applications requiring simultaneous control of mechanical strain and electrical properties.