Intrinsic Negative-U Centers in Freestanding LaAlO3/SrTiO3 Micro-membranes
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| Main Authors: | , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866909995374739456 |
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| author | Meucci, Giulia Konstantinopoulou, Pinelopi O. Jansen, Thies Nagda, Gunjan Carrad, Damon J. Di Gennaro, Emiliano Chen, Yu Manca, Nicola Bergeal, Nicolas Bibes, Manuel Kalaboukhov, Alexei Salluzzo, Marco Citro, Roberta Trier, Felix Pryds, Nini Granozio, Fabio Miletto Sambri, Alessia Jespersen, Thomas S. |
| author_facet | Meucci, Giulia Konstantinopoulou, Pinelopi O. Jansen, Thies Nagda, Gunjan Carrad, Damon J. Di Gennaro, Emiliano Chen, Yu Manca, Nicola Bergeal, Nicolas Bibes, Manuel Kalaboukhov, Alexei Salluzzo, Marco Citro, Roberta Trier, Felix Pryds, Nini Granozio, Fabio Miletto Sambri, Alessia Jespersen, Thomas S. |
| contents | The LaAlO3/SrTiO3 (LAO/STO) interface hosts a rich range of electronic phenomena, including unconventional electron pairing that in quantum dots gives rise to a negative effective charging energy U. Here, we show freestanding LAO/STO micro-membranes naturally hosting negative-U centers, where lateral confinement arises intrinsically, rather than from engineered nanostructures. These centers coexist with gate-tunable superconductivity and can remain stable upon thermal cycling from millikelvin temperatures to room temperature. Transport is in excellent agreement with calculations based on a negative-U Anderson model, and electrostatic simulations indicate characteristic center sizes of 20-80 nm. Our findings suggest that negative-U centers may arise from the intrinsic interfacial inhomogeneity typical of LAO/STO, and should therefore be considered a general feature of the LAO/STO interface. This could have important consequences for the microwave response of interfacial superconducting devices. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2601_13366 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Intrinsic Negative-U Centers in Freestanding LaAlO3/SrTiO3 Micro-membranes Meucci, Giulia Konstantinopoulou, Pinelopi O. Jansen, Thies Nagda, Gunjan Carrad, Damon J. Di Gennaro, Emiliano Chen, Yu Manca, Nicola Bergeal, Nicolas Bibes, Manuel Kalaboukhov, Alexei Salluzzo, Marco Citro, Roberta Trier, Felix Pryds, Nini Granozio, Fabio Miletto Sambri, Alessia Jespersen, Thomas S. Materials Science Mesoscale and Nanoscale Physics The LaAlO3/SrTiO3 (LAO/STO) interface hosts a rich range of electronic phenomena, including unconventional electron pairing that in quantum dots gives rise to a negative effective charging energy U. Here, we show freestanding LAO/STO micro-membranes naturally hosting negative-U centers, where lateral confinement arises intrinsically, rather than from engineered nanostructures. These centers coexist with gate-tunable superconductivity and can remain stable upon thermal cycling from millikelvin temperatures to room temperature. Transport is in excellent agreement with calculations based on a negative-U Anderson model, and electrostatic simulations indicate characteristic center sizes of 20-80 nm. Our findings suggest that negative-U centers may arise from the intrinsic interfacial inhomogeneity typical of LAO/STO, and should therefore be considered a general feature of the LAO/STO interface. This could have important consequences for the microwave response of interfacial superconducting devices. |
| title | Intrinsic Negative-U Centers in Freestanding LaAlO3/SrTiO3 Micro-membranes |
| topic | Materials Science Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2601.13366 |