Large-N theory of critical Fermi surface and strange metal

演讲人: Haoyu Guo Harvard University
时间: 2022-08-18 15:00-2022-08-18 16:00
地点:Conference Hall 104, Science Building, Tsinghua University

We describe the large N saddle point, and the structure of fluctuations about the saddle point, of a theory containing a sharp, critical Fermi surface in twospatial dimensions. The theory describes the onset of Ising order in a Fermi liquid, and closely related theories apply to other cases with critical Fermi surfaces. Inspired by SYK models, we employ random couplings in flavorspace between the fermions and the bosonic order parameter, but there is no spatial randomness: consequently, the G-Σ path integral of the theory is expressed in terms of fields bilocal in spacetime. We show by transport calculations that this first theory realizes a non-Fermi liquid but not a strange metal due to various cancellations related to momentum conservation. Next, we consider a theory with spatiallyrandom disorder, and demonstratethat it realizes a marginal Fermi liquid but not a strange metal. Finally, we propose that a strange metal can be realized by a theory with spatially random Yukawa interactions.