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[PAST EVENT] Physics Colloquium - Anton Burkov
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Anton Burkov, University of Waterloo, Title of talk: "Emergent symmetries, Luttinger's theorem and topology of metals.”
Abstract:
Luttinger's theorem connects a basic microscopic property of a given metallic crystalline material, the number of electrons per unit cell, to the volume, enclosed by its Fermi surface, which defines its low-energy observable properties. Such statements are valuable since, in general, deducing a low-energy description from microscopics, which may perhaps be regarded as the main problem of condensed matter theory, is far from easy.
In this talk I will describe a unified framework, which allows one to discuss Luttinger's theorems for ordinary metals, as well as closely analogous exact statements for topological semimetals, whose low-energy description contains either discrete point or continuous line nodes. This framework is based on the concept of a 't Hooft anomaly of the emergent symmetry, which characterizes the low-energy description of a given metallic phase.
The 't Hooft anomaly relates the low-energy theory of a metal to the topological response of a higher-dimensional symmetry-protected topological insulator.