Reversible structure manipulation by tuning carrier concentration in metastable Cu₂S

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Optimal material functionalities often emerge at phase transitions, where electronic and structural properties change simultaneously.
• Disentangling the driving forces (electronic vs. structural) behind phase transitions and controlling material properties remains experimentally challenging.

Purpose of the Study:

• To directly manipulate phase transitions in materials using a controlled experimental approach.
• To investigate the interplay between electronic structure and crystal symmetry during phase transitions.
• To demonstrate a nonthermal and reversible method for controlling material properties via phase transitions.

Main Methods:

• Utilized concurrent pumping and probing with an electron beam on copper sulfide (Cu₂S) nanoplates.
• Directly manipulated the transition between two distinct phases with different crystal symmetries and charge-carrier concentrations.

Main Results:

• Demonstrated that the electron beam can induce phase transitions by controlling charge generation and depletion.
• Showed that this manipulation is fully reversible and nonthermal in nature.
• Observed that electron-induced changes in electronic structure can lead to macroscopic crystal structure reconstruction.

Conclusions:

• Revealed a novel phase-transition pathway in materials driven by electron-induced electronic structure modification.
• Established a method for controlling material properties by manipulating phase transitions via electron beams.
• Highlighted the potential for using electronic changes to dictate macroscopic structural changes in materials.