Glide symmetry breaking and Ising criticality in the quasi-1D magnet CoNb
| Autor: | Michele, Fava, Radu, Coldea, S A, Parameswaran |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America |
| ISSN: | 1091-6490 |
| Popis: | Significance The quasi-1D magnetic insulator CoNb2O6 hosts a paradigmatic example of a quantum phase transition in the 1D Ising universality class. While the physics near the transition is largely insensitive to the microscopic Hamiltonian, several features observed in neutron-scattering experiments have hitherto remained unexplained. We propose a microscopic Hamiltonian that reproduces the entirety of the experimental phenomenology. This is based on a symmetry analysis of the material where a glide symmetry (translation composed with reflection) plays a crucial role. Strikingly, this sheds light on the microscopic mechanism of the transition itself, linking the Ising order to the breaking of both magnetic and spatial symmetries. We lay the groundwork for future high-precision investigations of Ising criticality, quasiparticle confinement, and quasiparticle decay in a quantum material. We construct a microscopic spin-exchange Hamiltonian for the quasi–one-dimensional (1D) Ising magnet CoNb2O6 that captures detailed and hitherto-unexplained aspects of its dynamic spin structure factor. We perform a symmetry analysis that recalls that an individual Ising chain in this material is buckled, with two sites in each unit cell related by a glide symmetry. Combining this with numerical simulations benchmarked against neutron scattering experiments, we argue that the single-chain Hamiltonian contains a staggered spin-exchange term. We further argue that the transverse-field–tuned quantum critical point in CoNb2O6 corresponds to breaking this glide symmetry, rather than an on-site Ising symmetry as previously believed. This gives a unified microscopic explanation of the dispersion of confined states in the ordered phase and quasiparticle breakdown in the polarized phase at high transverse field. |
| Databáze: | OpenAIRE |
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