Thermodynamics of the ultrafast phase transition of vanadium dioxide
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arXiv
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| Main Authors: | , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866918371062185984 |
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| author | Bagchi, Shreya Pastor, Ernest Santiso, José Johnson, Allan S. Wall, Simon E. |
| author_facet | Bagchi, Shreya Pastor, Ernest Santiso, José Johnson, Allan S. Wall, Simon E. |
| contents | Ultrafast photoexcitation is an emerging route to selective control of phase transitions. However, it is difficult to determine which modes govern the transformation and how effectively they are targeted by photoexcitation. This is exemplified in vanadium dioxide, which transitions from a monoclinic insulator to a rutile metal upon heating or photoexcitation. There is a long-standing debate about whether this transition is electronically or structurally driven and whether the structural component is coherent, driven by a single structural mode or thermal in nature. In this work, we develop a simple thermodynamic framework based on temperature-dependent ultrafast pump-probe measurements and contrast it to microscopic-detail-free modelling to identify the driving mechanism of the transition, revealing that population of the full thermal phonon spectrum, especially high-frequency oxygen modes, is necessary to stabilize the metallic phase. Our approach can straightforwardly be applied to determine the nature of other photoinduced phase transitions without the need for complex multi-messenger experiments and can guide new control strategies, even for incoherent transitions. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_04600 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Thermodynamics of the ultrafast phase transition of vanadium dioxide Bagchi, Shreya Pastor, Ernest Santiso, José Johnson, Allan S. Wall, Simon E. Strongly Correlated Electrons Statistical Mechanics Optics Ultrafast photoexcitation is an emerging route to selective control of phase transitions. However, it is difficult to determine which modes govern the transformation and how effectively they are targeted by photoexcitation. This is exemplified in vanadium dioxide, which transitions from a monoclinic insulator to a rutile metal upon heating or photoexcitation. There is a long-standing debate about whether this transition is electronically or structurally driven and whether the structural component is coherent, driven by a single structural mode or thermal in nature. In this work, we develop a simple thermodynamic framework based on temperature-dependent ultrafast pump-probe measurements and contrast it to microscopic-detail-free modelling to identify the driving mechanism of the transition, revealing that population of the full thermal phonon spectrum, especially high-frequency oxygen modes, is necessary to stabilize the metallic phase. Our approach can straightforwardly be applied to determine the nature of other photoinduced phase transitions without the need for complex multi-messenger experiments and can guide new control strategies, even for incoherent transitions. |
| title | Thermodynamics of the ultrafast phase transition of vanadium dioxide |
| topic | Strongly Correlated Electrons Statistical Mechanics Optics |
| url | https://arxiv.org/abs/2603.04600 |