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| Main Authors: | , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2508.10267 |
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| _version_ | 1866912737292976128 |
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| author | Giuliano, Domenico Buccheri, Francesco |
| author_facet | Giuliano, Domenico Buccheri, Francesco |
| contents | We study the boundary phase diagram and the low-temperature heat and magnetization transport at a $Y$-junction of XX spin chains. Depending on the magnetization axis anisotropy between the magnetic exchange interactions at the junction, the system exhibits two different strong-coupling regimes at low energies/temperatures, similar to the overscreened (topological) four- and to the two-channel Kondo fixed points. Using renormalization group arguments combined with boundary conformal field theory methods, we show the instability of the former under any XY-type anisotropy at the junction. We analyze the low-temperature spin and the heat conductances. We find evidence of spin fractionalization of the elementary excitations at the four-channel Kondo fixed point by means of the magnetic Wiedemann-Franz law. We caution that the instability under XY anisotropy may hinder the detection of the phenomenology related to the four-channel Kondo effect, therefore requiring careful control in experimental realizations. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_10267 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Spin and thermal current scaling at a $Y$-junction of XX spin chains Giuliano, Domenico Buccheri, Francesco Strongly Correlated Electrons We study the boundary phase diagram and the low-temperature heat and magnetization transport at a $Y$-junction of XX spin chains. Depending on the magnetization axis anisotropy between the magnetic exchange interactions at the junction, the system exhibits two different strong-coupling regimes at low energies/temperatures, similar to the overscreened (topological) four- and to the two-channel Kondo fixed points. Using renormalization group arguments combined with boundary conformal field theory methods, we show the instability of the former under any XY-type anisotropy at the junction. We analyze the low-temperature spin and the heat conductances. We find evidence of spin fractionalization of the elementary excitations at the four-channel Kondo fixed point by means of the magnetic Wiedemann-Franz law. We caution that the instability under XY anisotropy may hinder the detection of the phenomenology related to the four-channel Kondo effect, therefore requiring careful control in experimental realizations. |
| title | Spin and thermal current scaling at a $Y$-junction of XX spin chains |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2508.10267 |