Berezinskii-Kosterlitz-Thouless transition with enhanced phase stiffness in $d$-wave strongly coupled two-dimensional superconductors
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arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| author | Paramasivam, Sathish Kumar Perali, Andrea Milošević, Milorad V. |
| author_facet | Paramasivam, Sathish Kumar Perali, Andrea Milošević, Milorad V. |
| contents | We reveal the key role of the $d$-wave symmetry of the superconducting gap in strongly coupled two-dimensional superconductors in determining the properties of the Berezinskii-Kosterlitz-Thouless (BKT) transition, associated with a sizable enhancement of the phase stiffness compared to nodeless-gap superconductors. The enhanced stiffness originates from extended regions of vanishing gap around the nodal lines of the Brillouin zone (BZ). Our study, based on mean-field and BKT theory, presents a comparative analysis of $s$-wave and $d$-wave scenarios, highlighting the features of the latter that boost the stiffness and the BKT transition temperature (T$_{BKT}$). The comparison focuses on two quantities: the mean-field critical temperature and the maximum superconducting gap related to the pairing strengths. We present a phase diagram showing the scaling of T$_{BKT}$ with respect to the mean-field critical temperature across the BCS-BEC crossover and the evolution of the pseudogap. We also present a zero-temperature phase-stiffness intensity map over the Brillouin zone, displaying a two-component structure consisting of low- and high-stiffness regions whose extent depends on microscopic parameters. These results identify the nodal gap structure of strongly coupled two-dimensional superconductors as a key mechanism enabling enhanced stiffness and elevated T$_{BKT}$ compared to their $s$-wave counterparts. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_16385 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Berezinskii-Kosterlitz-Thouless transition with enhanced phase stiffness in $d$-wave strongly coupled two-dimensional superconductors Paramasivam, Sathish Kumar Perali, Andrea Milošević, Milorad V. Superconductivity We reveal the key role of the $d$-wave symmetry of the superconducting gap in strongly coupled two-dimensional superconductors in determining the properties of the Berezinskii-Kosterlitz-Thouless (BKT) transition, associated with a sizable enhancement of the phase stiffness compared to nodeless-gap superconductors. The enhanced stiffness originates from extended regions of vanishing gap around the nodal lines of the Brillouin zone (BZ). Our study, based on mean-field and BKT theory, presents a comparative analysis of $s$-wave and $d$-wave scenarios, highlighting the features of the latter that boost the stiffness and the BKT transition temperature (T$_{BKT}$). The comparison focuses on two quantities: the mean-field critical temperature and the maximum superconducting gap related to the pairing strengths. We present a phase diagram showing the scaling of T$_{BKT}$ with respect to the mean-field critical temperature across the BCS-BEC crossover and the evolution of the pseudogap. We also present a zero-temperature phase-stiffness intensity map over the Brillouin zone, displaying a two-component structure consisting of low- and high-stiffness regions whose extent depends on microscopic parameters. These results identify the nodal gap structure of strongly coupled two-dimensional superconductors as a key mechanism enabling enhanced stiffness and elevated T$_{BKT}$ compared to their $s$-wave counterparts. |
| title | Berezinskii-Kosterlitz-Thouless transition with enhanced phase stiffness in $d$-wave strongly coupled two-dimensional superconductors |
| topic | Superconductivity |
| url | https://arxiv.org/abs/2511.16385 |