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arXiv · 2002.01947

Gauge Theories for the Thermal Hall Effect

Haoyu Guo·Rhine Samajdar·Mathias S. Scheurer·Subir Sachdev
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Abstract

We consider the thermal Hall effect of fermionic matter coupled to emergent gauge fields in 2+1 dimensions. While the low-temperature thermal Hall conductivity of bulk topological phases can be connected to chiral edge states and a gravitational anomaly, there is no such interpretation at nonzero temperatures above 2+1 dimensional quantum critical points. In the limit of a large number of matter flavors, the leading contribution to the thermal Hall conductivity is that from the fermionic matter. The next-to-leading contribution is from the gauge fluctuations, and this has a sign which is opposite to that of the matter contribution. We illustrate this by computations on a Dirac Chern-Simons theory of the quantum phase transition in a square-lattice antiferromagnet involving the onset of semion topological order. We find similar results for a model of the pseudogap metal with Fermi pockets coupled to an emergent U(1) gauge field. We note connections to recent observations on the hole-doped cuprates: our theory captures the main trends, but the overall magnitude of the effect is smaller than that observed.

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Haoyu Guo, Rhine Samajdar, Mathias S. Scheurer, Subir Sachdev. 2020-02-05. Gauge Theories for the Thermal Hall Effect. https://doi.org/10.1103/physrevb.101.195126

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