Electrically switchable vacancy state revealed by in-operando positron experiments
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| Main Authors: | , , , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866913056675594240 |
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| author | Fulop, Ric Lyons IV, Laurence Nick, Robert Weber, Marc H. Liu, Ming Atikian, Haig Bauer, Uwe Barbati, Alexander C. Gershenfeld, Neil |
| author_facet | Fulop, Ric Lyons IV, Laurence Nick, Robert Weber, Marc H. Liu, Ming Atikian, Haig Bauer, Uwe Barbati, Alexander C. Gershenfeld, Neil |
| contents | 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 formation and reveals a void to cluster relaxation hierarchy. The current-induced vacancy concentration exceeds the thermal-equilibrium value at 352C by > 106x, is present only while current is applied, and vanishes within minutes. The nucleation rate scales steeply with the applied current, connecting the minute-scale kinetics resolved here to the sub-second flash events observed in ceramic sintering. These results demonstrate current-induced Frenkel-pair production in a metal and identify a defect-mediated, non-equilibrium contribution to the flash state. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_21283 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Electrically switchable vacancy state revealed by in-operando positron experiments Fulop, Ric Lyons IV, Laurence Nick, Robert Weber, Marc H. Liu, Ming Atikian, Haig Bauer, Uwe Barbati, Alexander C. Gershenfeld, Neil Materials Science Applied Physics 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 formation and reveals a void to cluster relaxation hierarchy. The current-induced vacancy concentration exceeds the thermal-equilibrium value at 352C by > 106x, is present only while current is applied, and vanishes within minutes. The nucleation rate scales steeply with the applied current, connecting the minute-scale kinetics resolved here to the sub-second flash events observed in ceramic sintering. These results demonstrate current-induced Frenkel-pair production in a metal and identify a defect-mediated, non-equilibrium contribution to the flash state. |
| title | Electrically switchable vacancy state revealed by in-operando positron experiments |
| topic | Materials Science Applied Physics |
| url | https://arxiv.org/abs/2604.21283 |