Broken discrete and continuous symmetries in two dimensional spiral antiferromagnets
We study the occurrence of symmetry breakings, at zero and finite temperatures, in the J1-J3 antiferromagnetic Heisenberg model on the square lattice using Schwinger boson mean field theory. For spin 1/2 the ground state breaks always the SU(2) symmetry with a continuous quasi-critical transition at...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2013 |
| País: | Argentina |
| Institución: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repositorio: | CONICET Digital (CONICET) |
| Idioma: | inglés |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/5910 |
| Acceso en línea: | http://hdl.handle.net/11336/5910 |
| Access Level: | acceso abierto |
| Palabra clave: | Mott Insulator Magnetic Frustration https://purl.org/becyt/ford/1.3 https://purl.org/becyt/ford/1 |
| Sumario: | We study the occurrence of symmetry breakings, at zero and finite temperatures, in the J1-J3 antiferromagnetic Heisenberg model on the square lattice using Schwinger boson mean field theory. For spin 1/2 the ground state breaks always the SU(2) symmetry with a continuous quasi-critical transition at J3/J1 ~ 0.38,from Neel to spiral long range order, although local spin fluctuations considerations suggest an intermediate disordered regime around 0.35 ~ J3/J1 ~ 0.5, in qualitative agreement with recent numerical results. At low temperatures we find a Z2 broken symmetry region with short range spiral order characterized by an Ising-like nematic order parameter that compares qualitatively well with classical Monte Carlo results. At intermediate temperatures the phase diagram shows regions with collinear short range orders: for J3/J1 < 1 Neel (pi,pi) correlations and for J3/J1 > 1 a novel phase consisting of four decoupled third neighbour sublattices with Neel (pi,pi)_4 correlations in each one. We conclude that the effect of quantum and thermal fluctuations is to favour collinear correlations even in the strongly frustrated regime. |
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