Spectral singularities of spinon dynamics in higher dimensions.

Title: Spectral singularities of spinon dynamics in higher dimensions.
Speaker: Prof. Masafumi Udagawa (Department of Physics, Gakushuin University)
Start Date/Time: 2023-03-01 / 09:30 (Taipei time)
End Date/Time: 2023-03-01 / 11:30
Host: Prof. Yi-Ping Huang (NTHU)

Online Zoom Link: https://us02web.zoom.us/j/86867205231?pwd=OTJVTURuVU9FVzkzR01kMVUwcGVvZz09
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Spinon is a typical fractional excitation that appears in a broad range of quantum spin liquid (QSL) phases.Despite its ubiquity, theoretical description of spinon dynamics still remains quite elusive, especially in higher dimensions.In this contribution, we address the spinon dynamics in an intermediate temperature range, where the coherency of QSL state is still not developed, while the spinons already show coherent quantum motion.In this region, the spinon dynamics exhibits characteristic singularities that affect the response functions such as the dynamical structure factor.We developed an analytical scheme which we named a state graph mapping, and combined it with numerical approaches to address the singularities of the spinon spectrum in a class of frustrated magnetic systems defined on pyrochlore and kagome lattices.In this talk, we especially focus on the van-Hove singularity of spinons and the resultant spectral edge discontinuity in quantum spin ice, and discuss its relevance to experiments.