Symmetry and topology of quasiparticles and their bound states in correlated insulators

Speaker: Sid Parameswaran, University of Oxford

When: November 20, 2020 (Fri), 12:00PM to 01:00PM (add to my calendar)

This event is part of the Biophysics/Condensed Matter Seminar Series.

: In this talk, I explore two examples of how the symmetry of a microscopic lattice or topology of an underlying non-interacting band structure can be imprinted in the excitations of strongly-correlated insulators. First, I show that previously-unnoticed crystal symmetry constraints drastically alter the understanding of Ising quantum criticality in the quasi-1D magnetic insulator CoNb2O6, resolving decade-old puzzles related to the dispersion of confined `kinks’ in the ordered phase and the decay of spin-flip quasiparticles in the paramagnetic phase [1]. I will then change focus to the correlated quantum anomalous Hall insulator recently observed in twisted bilayer graphene near the magic angle, where I will discuss the topological properties [2] and many-body physics [3] of excitonic bound states.

References: [1] M. Fava, R. Coldea, and S.A. Parameswaran, Proc. Nat. Acad. Sci. USA 117, 25219 (2020).. [2] Y.H. Kwan, Y. Hu, S.H. Simon, and S.A. Parameswaran, arXiv:2003.11560 (2020). [3] Y.H. Kwan, Y. Hu, S.H. Simon, and S.A. Parameswaran, arXiv:2003.11559 (2020).