Copper wire develops a massive population of missing atoms when hit with a specific electrical current, effectively melting its internal structure without heat.
April 24, 2026
Original Paper
Electrically switchable vacancy state revealed by in-operando positron experiments
arXiv · 2604.21283
The Takeaway
Electrical currents applied to copper generate a surge of atomic vacancies one million times higher than what is found at thermal equilibrium. These holes in the metal crystal structure exist only while the electricity is flowing and disappear minutes after the power stops. This electrically switchable state means the metal can be softened or modified on demand without needing extreme temperatures. Traditionally, vacancies are created by intense heat or radiation, making them permanent defects. Mastering this effect could allow for self-healing electronics or materials that change their strength the moment a switch is flipped.
From the abstract
Whether the flash state in electrically driven solids involves non-equilibrium defect production or is accounted for by Joule heating alone has been debated since 2010. Using positron annihilation spectroscopy on copper, we observe a fully reversible, electrically switchable vacancy population: the DBS S-parameter rises above baseline whenever applied current exceeds a critical density and returns on current removal. Positron lifetime spectroscopy independently confirms open-volume defect format