Thermodynamic Discovery of Tetracriticality and Emergent Multicomponent Superconductivity in UTe$_2$
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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_ | 1866914406940540928 |
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| author | Kamat, Sahas Dans, Jared Saha, Shanta Kokovin, Artem D. Paglione, Johnpierre Schmalian, Jörg Ramshaw, B. J. |
| author_facet | Kamat, Sahas Dans, Jared Saha, Shanta Kokovin, Artem D. Paglione, Johnpierre Schmalian, Jörg Ramshaw, B. J. |
| contents | The candidate topological superconductor UTe$_2$ exhibits a complex phase diagram with multiple superconducting states, yet the nature of their coexistence has remained a central mystery. In particular, the apparent intersection of two second-order phase boundaries at a ``triple point'' in the pressure-temperature phase diagram is thermodynamically forbidden, suggesting hidden phase transitions or a fundamental misunderstanding of the superconductivity in UTe$_2$. Here, we use pulse-echo ultrasound to resolve this puzzle by discovering a new phase boundary that is characterized by a unique ``upward jump" in the sound velocity -- direct thermodynamic evidence for a re-entrant phase transition. Our results establish $\left(P^{\star},T^{\star}\right)$ as a tetracrtical point, beyond which the ambient and pressure-induced superconducting order parameters form a multi-component state. We use the measured phase diagram to construct a Ginzburg-Landau theory that shows that strong competition between the two superconducting order parameters drives the re-entrance and leads to phase locking that suppress superconducting fluctuations. These findings provide the definitive magnetic field-temperature-pressure phase diagram and establish a thermodynamic foundation for multi-component -- and potentially topological -- superconductivity in UTe$_2$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_17905 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Thermodynamic Discovery of Tetracriticality and Emergent Multicomponent Superconductivity in UTe$_2$ Kamat, Sahas Dans, Jared Saha, Shanta Kokovin, Artem D. Paglione, Johnpierre Schmalian, Jörg Ramshaw, B. J. Superconductivity The candidate topological superconductor UTe$_2$ exhibits a complex phase diagram with multiple superconducting states, yet the nature of their coexistence has remained a central mystery. In particular, the apparent intersection of two second-order phase boundaries at a ``triple point'' in the pressure-temperature phase diagram is thermodynamically forbidden, suggesting hidden phase transitions or a fundamental misunderstanding of the superconductivity in UTe$_2$. Here, we use pulse-echo ultrasound to resolve this puzzle by discovering a new phase boundary that is characterized by a unique ``upward jump" in the sound velocity -- direct thermodynamic evidence for a re-entrant phase transition. Our results establish $\left(P^{\star},T^{\star}\right)$ as a tetracrtical point, beyond which the ambient and pressure-induced superconducting order parameters form a multi-component state. We use the measured phase diagram to construct a Ginzburg-Landau theory that shows that strong competition between the two superconducting order parameters drives the re-entrance and leads to phase locking that suppress superconducting fluctuations. These findings provide the definitive magnetic field-temperature-pressure phase diagram and establish a thermodynamic foundation for multi-component -- and potentially topological -- superconductivity in UTe$_2$. |
| title | Thermodynamic Discovery of Tetracriticality and Emergent Multicomponent Superconductivity in UTe$_2$ |
| topic | Superconductivity |
| url | https://arxiv.org/abs/2603.17905 |