An unusual first order phase transition in a 2D superconductor
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arXiv
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| Autores principales: | , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| _version_ | 1866917928692088832 |
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| author | Jabusch, Noah J. Kokkinis, Emmanouil K. Chubukov, Andrey V. |
| author_facet | Jabusch, Noah J. Kokkinis, Emmanouil K. Chubukov, Andrey V. |
| contents | We consider a superconductor under external perturbation, which forces Cooper pairs to develop with a finite total momentum $q$. The condensation energy of such a state decreases with $q$ and vanishes at a critical $q_c$. We analyze how superconducting order evolves at $ q \approx q_c$. In 3D, the result is well-known: the pairing susceptibility diverges at $q = q_c +0$, and the gap amplitude $Δ(q)$ gradually increases as $q$ decreases below $q_c$ and reaches its largest value $Δ_0$ at $q=0$. In 2D, we find different behavior. Namely, for a parabolic dispersion, the pairing susceptibility also diverges at $q = q_c +0$, but at $q = q_c -0$, the gap amplitude jumps to the maximal $Δ_0$ and remains equal to it for all $q <q_c$. For a non-parabolic dispersion $\varepsilon_{k}= c k^{2α}$, we find that for $α>1$ the transition becomes second-order, but the gap evolution is rather sharp, whereas for $α<1$ it becomes first-order, but $Δ(q)$ is non-monotonic. This is similar, but not identical, to the behavior of magnetization near a Stoner transition in 2D. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2502_13265 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | An unusual first order phase transition in a 2D superconductor Jabusch, Noah J. Kokkinis, Emmanouil K. Chubukov, Andrey V. Superconductivity We consider a superconductor under external perturbation, which forces Cooper pairs to develop with a finite total momentum $q$. The condensation energy of such a state decreases with $q$ and vanishes at a critical $q_c$. We analyze how superconducting order evolves at $ q \approx q_c$. In 3D, the result is well-known: the pairing susceptibility diverges at $q = q_c +0$, and the gap amplitude $Δ(q)$ gradually increases as $q$ decreases below $q_c$ and reaches its largest value $Δ_0$ at $q=0$. In 2D, we find different behavior. Namely, for a parabolic dispersion, the pairing susceptibility also diverges at $q = q_c +0$, but at $q = q_c -0$, the gap amplitude jumps to the maximal $Δ_0$ and remains equal to it for all $q <q_c$. For a non-parabolic dispersion $\varepsilon_{k}= c k^{2α}$, we find that for $α>1$ the transition becomes second-order, but the gap evolution is rather sharp, whereas for $α<1$ it becomes first-order, but $Δ(q)$ is non-monotonic. This is similar, but not identical, to the behavior of magnetization near a Stoner transition in 2D. |
| title | An unusual first order phase transition in a 2D superconductor |
| topic | Superconductivity |
| url | https://arxiv.org/abs/2502.13265 |