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Two-dimensional quantum antiferromagnets host rich physics including long-range ordering, high-Tc superconductivity, quantum spin liquid behavior, topological ordering, variety of other exotic phases, and quantum criticalities. Here we develop a method to describe the quantum antiferromagnets using fermionic degrees of freedom. The method is based on a formally exact mapping between spin-exchange models and theories describing fermionic matter with the emergent U(1) Chern-Simons gauge field. For the planar Neel state, this mapping self-consistently generates the Chern-Simons superconductor mean-field ground state of the introduced fermions. Moreover, we show that confinement-deconfinement transitions in frustrated quantum magnets are signaled and characterized by the Chern-Simons superconductor’s instabilities, resulting in possible topological ordered states described by certain Chern-Simons bosonic orders. Our method provides a systematic parton mean-field description for the magnetically ordered state, the spin-liquids, and the unconventional phase transitions between them in a unified physical picture.
Dr. Wang, Rui obtained Ph. D. from Nanjing University in 2017. He worked as a visiting scholar in Hong Kong University and University of Houston from 2015 to 2017, and from 2017 to 2019 he was a postdoc in Shanghai Jiao Tong University, after which he joined Nanjing University. His main research is on strongly-correlated topological phases, including topological semimetals, superconductors, as well as quantum spin liquids. His recent studies were focused on (1) Kondo-related problems in topological phases of matters, e.g., the quantum impurity in spin liquids, (2) Novel theories on frustrated quantum magnets, including new parton mean-field theories and predictions of spontaneous fractionalization in hardcore boson systems. To date, he published 27 papers in peer reviewed journals, including 2 PRL, 3 Nature Communications, 1 Nano Letters, 14 PRB.
References:
[1]Rui Wang, et al, Kondo Signatures of a Quantum Magnetic Impurity in Topological Superconductors, Phys. Rev. Lett, 122, 087001 (2019).
[2] Rui Wang, et al, Chern-Simons superconductors and their instabilities, arXiv: 2010.10067 (2020).
[3] Rui Wang, et al, Chern-Simons fermionization approach to two-dimensional quantum magnets: Implications for antiferromagnetic magnons and unconventional quantum phase transitions, Phys. Rev. B 98, 064402 (2018).
Note: Prof. Wang will stay here until Nov. 16. Please feel free to have a private meeting with the speaker if you are interested.