Duality and domain wall dynamics in a twisted Kitaev chain
| Autor: | Tyrel M. McQueen, Jason W. Krizan, C. M. Morris, J. Viirok, N. P. Armitage, Nisheeta Desai, Ribhu K. Kaul, Toomas Rõõm, Urmas Nagel, D. Hüvonen, Robert J. Cava, Seyed Koohpayeh |
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| Rok vydání: | 2020 |
| Předmět: |
Physics
Condensed matter physics Strongly Correlated Electrons (cond-mat.str-el) media_common.quotation_subject Spontaneous symmetry breaking General Physics and Astronomy Frustration Duality (optimization) FOS: Physical sciences Renormalization group Domain wall (string theory) Condensed Matter - Strongly Correlated Electrons Ising model Quantum spin liquid Spin (physics) media_common |
| DOI: | 10.48550/arxiv.2009.14189 |
| Popis: | The Ising chain in transverse field is a paradigmatic model for a host of physical phenomena, including spontaneous symmetry breaking, topological defects, quantum criticality, and duality. Although the quasi-1D ferromagnet CoNb$_2$O$_6$ has been put forward as the best material example of the transverse field Ising model, it exhibits significant deviations from ideality. Through a combination of THz spectroscopy and theory, we show that CoNb$_2$O$_6$ in fact is well described by a different model with strong bond dependent interactions, which we dub the {\it twisted Kitaev chain}, as these interactions share a close resemblance to a one-dimensional version of the intensely studied honeycomb Kitaev model. In this model the ferromagnetic ground state of CoNb$_2$O$_6$ arises from the compromise between two distinct alternating axes rather than a single easy axis. Due to this frustration, even at zero applied field domain-wall excitations have quantum motion that is described by the celebrated Su-Schriefer-Heeger model of polyacetylene. This leads to rich behavior as a function of field. Despite the anomalous domain wall dynamics, close to a critical transverse field the twisted Kitaev chain enters a universal regime in the Ising universality class. This is reflected by the observation that the excitation gap in CoNb$_2$O$_6$ in the ferromagnetic regime closes at a rate precisely twice that of the paramagnet. This originates in the duality between domain walls and spin-flips and the topological conservation of domain wall parity. We measure this universal ratio `2' to high accuracy -- the first direct evidence for the Kramers-Wannier duality in nature. Comment: 6 pages, 3 figures; 5 pages, 7 figures (Supplemental) |
| Databáze: | OpenAIRE |
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