Symmetry induced pairing in dark excitonic condensate at finite temperature
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866913994755801088 |
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| author | Alkady, Adham Kuklov, Anatoly B. |
| author_facet | Alkady, Adham Kuklov, Anatoly B. |
| contents | Bose Einstein condensate of dark intervalley excitons must be inherently multi-component because of crystalline symmetries. Since valleys hosting such excitons are separated by large quasi-momenta, a minimal inter-component Josephson-type coupling can only be established between pairs of excitons from the time-reversed valleys. As a result, a paired condensate can emerge at finite temperature, that is, the off-diagonal order exists for the pairs from the time-reversed valleys, while the individual valleys are disordered. This prediction follows from the elementary mean field analysis regardless of the dimensionality. However, as Monte Carlo simulations show, no such a phase exists in 3D crystals. Instead, the multi-component condensation proceeds as the Ist order transition from the normal state. The paired phase does exist in 2D for the number of the components $N_v\geq 6$. It forms by Berezinskii-Kosterlitz-Thouless transition from the high temperature (normal) phase. The multi-component condensate appears upon further lowering of temperature. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2505_00120 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Symmetry induced pairing in dark excitonic condensate at finite temperature Alkady, Adham Kuklov, Anatoly B. Statistical Mechanics Optics Bose Einstein condensate of dark intervalley excitons must be inherently multi-component because of crystalline symmetries. Since valleys hosting such excitons are separated by large quasi-momenta, a minimal inter-component Josephson-type coupling can only be established between pairs of excitons from the time-reversed valleys. As a result, a paired condensate can emerge at finite temperature, that is, the off-diagonal order exists for the pairs from the time-reversed valleys, while the individual valleys are disordered. This prediction follows from the elementary mean field analysis regardless of the dimensionality. However, as Monte Carlo simulations show, no such a phase exists in 3D crystals. Instead, the multi-component condensation proceeds as the Ist order transition from the normal state. The paired phase does exist in 2D for the number of the components $N_v\geq 6$. It forms by Berezinskii-Kosterlitz-Thouless transition from the high temperature (normal) phase. The multi-component condensate appears upon further lowering of temperature. |
| title | Symmetry induced pairing in dark excitonic condensate at finite temperature |
| topic | Statistical Mechanics Optics |
| url | https://arxiv.org/abs/2505.00120 |