Valence Bonds in Random Quantum Magnets: Theory and Application to
We analyze the effect of quenched disorder on spin-1/2 quantum magnets in which magnetic frustration promotes the formation of local singlets. Our results include a theory for 2D valence-bond solids subject to weak bond randomness, as well as extensions to stronger disorder regimes where we make con...
| Main Authors: | , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
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American Physical Society
2018
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| Online Access: | http://hdl.handle.net/1721.1/117213 https://orcid.org/0000-0002-3488-4532 |
| _version_ | 1811081793868136448 |
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| author | Senthil, T. Kimchi, Itamar Nahum, Adam |
| author2 | Massachusetts Institute of Technology. Department of Mathematics |
| author_facet | Massachusetts Institute of Technology. Department of Mathematics Senthil, T. Kimchi, Itamar Nahum, Adam |
| author_sort | Senthil, T. |
| collection | MIT |
| description | We analyze the effect of quenched disorder on spin-1/2 quantum magnets in which magnetic frustration promotes the formation of local singlets. Our results include a theory for 2D valence-bond solids subject to weak bond randomness, as well as extensions to stronger disorder regimes where we make connections with quantum spin liquids. We find, on various lattices, that the destruction of a valence-bond solid phase by weak quenched disorder leads inevitably to the nucleation of topological defects carrying spin-1/2 moments. This renormalizes the lattice into a strongly random spin network with interesting low-energy excitations. Similarly, when short-ranged valence bonds would be pinned by stronger disorder, we find that this putative glass is unstable to defects that carry spin-1/2 magnetic moments, and whose residual interactions decide the ultimate low-energy fate. Motivated by these results we conjecture Lieb-Schultz-Mattis-like restrictions on ground states for disordered magnets with spin 1/2 per statistical unit cell. These conjectures are supported by an argument for 1D spin chains. We apply insights from this study to the phenomenology of YbMgGaO_{4}, a recently discovered triangular lattice spin-1/2 insulator which was proposed to be a quantum spin liquid. We instead explore a description based on the present theory. Experimental signatures, including unusual specific heat, thermal conductivity, and dynamical structure factor, and their behavior in a magnetic field, are predicted from the theory, and compare favorably with existing measurements on YbMgGaO_{4} and related materials. |
| first_indexed | 2024-09-23T11:52:14Z |
| format | Article |
| id | mit-1721.1/117213 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T11:52:14Z |
| publishDate | 2018 |
| publisher | American Physical Society |
| record_format | dspace |
| spelling | mit-1721.1/1172132022-09-27T22:32:16Z Valence Bonds in Random Quantum Magnets: Theory and Application to Senthil, T. Kimchi, Itamar Nahum, Adam Massachusetts Institute of Technology. Department of Mathematics Massachusetts Institute of Technology. Department of Physics Kimchi, Itamar Nahum, Adam We analyze the effect of quenched disorder on spin-1/2 quantum magnets in which magnetic frustration promotes the formation of local singlets. Our results include a theory for 2D valence-bond solids subject to weak bond randomness, as well as extensions to stronger disorder regimes where we make connections with quantum spin liquids. We find, on various lattices, that the destruction of a valence-bond solid phase by weak quenched disorder leads inevitably to the nucleation of topological defects carrying spin-1/2 moments. This renormalizes the lattice into a strongly random spin network with interesting low-energy excitations. Similarly, when short-ranged valence bonds would be pinned by stronger disorder, we find that this putative glass is unstable to defects that carry spin-1/2 magnetic moments, and whose residual interactions decide the ultimate low-energy fate. Motivated by these results we conjecture Lieb-Schultz-Mattis-like restrictions on ground states for disordered magnets with spin 1/2 per statistical unit cell. These conjectures are supported by an argument for 1D spin chains. We apply insights from this study to the phenomenology of YbMgGaO_{4}, a recently discovered triangular lattice spin-1/2 insulator which was proposed to be a quantum spin liquid. We instead explore a description based on the present theory. Experimental signatures, including unusual specific heat, thermal conductivity, and dynamical structure factor, and their behavior in a magnetic field, are predicted from the theory, and compare favorably with existing measurements on YbMgGaO_{4} and related materials. 2018-07-31T14:25:00Z 2018-07-31T14:25:00Z 2018-07 2018-04 2018-07-29T18:00:20Z Article http://purl.org/eprint/type/JournalArticle 2160-3308 http://hdl.handle.net/1721.1/117213 Kimchi, Itamar, Adam Nahum and T. Senthil. "Valence Bonds in Random Quantum Magnets: Theory and Application to YbMgGaO₄." Physical Review X 8 (2018), 031028. https://orcid.org/0000-0002-3488-4532 en http://dx.doi.org/10.1103/PhysRevX.8.031028 Physical Review X Creative Commons Attribution http://creativecommons.org/licenses/by/3.0 application/pdf American Physical Society American Physical Society |
| spellingShingle | Senthil, T. Kimchi, Itamar Nahum, Adam Valence Bonds in Random Quantum Magnets: Theory and Application to |
| title | Valence Bonds in Random Quantum Magnets: Theory and Application to |
| title_full | Valence Bonds in Random Quantum Magnets: Theory and Application to |
| title_fullStr | Valence Bonds in Random Quantum Magnets: Theory and Application to |
| title_full_unstemmed | Valence Bonds in Random Quantum Magnets: Theory and Application to |
| title_short | Valence Bonds in Random Quantum Magnets: Theory and Application to |
| title_sort | valence bonds in random quantum magnets theory and application to |
| url | http://hdl.handle.net/1721.1/117213 https://orcid.org/0000-0002-3488-4532 |
| work_keys_str_mv | AT senthilt valencebondsinrandomquantummagnetstheoryandapplicationto AT kimchiitamar valencebondsinrandomquantummagnetstheoryandapplicationto AT nahumadam valencebondsinrandomquantummagnetstheoryandapplicationto |