Theta electromagnetism in quantum spin ice: Microscopic analysis of improper symmetries
Fuente:
arXiv
Salvato in:
| Autori principali: | , , |
|---|---|
| Natura: | Preprint |
| Pubblicazione: |
2025
|
| Soggetti: | |
| Accesso online: | |
| Tags: |
Aggiungi Tag
Nessun Tag, puoi essere il primo ad aggiungerne!!
|
| _version_ | 1866913929101312000 |
|---|---|
| author | Naik, Gautam K. Hallén, Jonathan N. Laumann, Chris R. |
| author_facet | Naik, Gautam K. Hallén, Jonathan N. Laumann, Chris R. |
| contents | $U(1)$ gauge theories, including conventional Maxwell electromagnetism, allow $θ$-terms when parity and time-reversal symmetry are broken. In condensed matter systems, the physics of $θ$ as a magnetoelectric response has been explored extensively within the context of topological insulators and multiferroics. We show how $θ$-terms can arise in the internal dynamics of the emergent electromagnetism in a $U(1)$ quantum spin liquid. In its Coulomb phase, the minimal model of pyrochlore quantum spin ice is governed by a six-spin ring exchange Hamiltonian. We identify the next-order contribution to the microscopic Hamiltonian when parity, time-reversal, and all improper spatial symmetries are broken -- a seven-spin term which leads to a two-parameter lattice gauge theory with a $θ$-electromagnetic phase. We derive how the seven-spin term is generated perturbatively within each of the three symmetry classes of short-range pyrochlore spin ice. Within a complete microscopic symmetry analysis, we find that the most general nearest-neighbor Hamiltonians fail to generate the seven-spin term, and one must include next-nearest-neighbor interactions to obtain an emergent $θ$. Using gauge mean-field theory we compute additional contributions to the $θ$-term from the spinon sector. Finally, we determine the conditions required for an internal $θ$-term to generate a significant external magnetoelectic response. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2502_19482 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Theta electromagnetism in quantum spin ice: Microscopic analysis of improper symmetries Naik, Gautam K. Hallén, Jonathan N. Laumann, Chris R. Strongly Correlated Electrons $U(1)$ gauge theories, including conventional Maxwell electromagnetism, allow $θ$-terms when parity and time-reversal symmetry are broken. In condensed matter systems, the physics of $θ$ as a magnetoelectric response has been explored extensively within the context of topological insulators and multiferroics. We show how $θ$-terms can arise in the internal dynamics of the emergent electromagnetism in a $U(1)$ quantum spin liquid. In its Coulomb phase, the minimal model of pyrochlore quantum spin ice is governed by a six-spin ring exchange Hamiltonian. We identify the next-order contribution to the microscopic Hamiltonian when parity, time-reversal, and all improper spatial symmetries are broken -- a seven-spin term which leads to a two-parameter lattice gauge theory with a $θ$-electromagnetic phase. We derive how the seven-spin term is generated perturbatively within each of the three symmetry classes of short-range pyrochlore spin ice. Within a complete microscopic symmetry analysis, we find that the most general nearest-neighbor Hamiltonians fail to generate the seven-spin term, and one must include next-nearest-neighbor interactions to obtain an emergent $θ$. Using gauge mean-field theory we compute additional contributions to the $θ$-term from the spinon sector. Finally, we determine the conditions required for an internal $θ$-term to generate a significant external magnetoelectic response. |
| title | Theta electromagnetism in quantum spin ice: Microscopic analysis of improper symmetries |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2502.19482 |