Thermal Hall effect in square-lattice spin liquids: an application to cuprates

Recent experiments [1] have revealed an enhanced thermal Hall effect in the pseudogap phase of several different cuprates compounds. The large signal even persists in the undoped system and, thus, challenges our understanding of the antiferromagnetic phase fundamentally. In this talk, I will analyze possible mechanisms that can give rise to a thermal Hall effect in the square-lattice Heisenberg antiferromagnet [2,3]. In particular, I will discuss the possibility [3] that the magnetic field drives the Néel state close to a transition to a phase where Néel order coexists with a chiral spin liquid. A spinon lattice model for this transition is shown to give rise to a large thermal Hall conductivity that also features a similar magnetic field and temperature dependence to experiment. We will derive the low-energy continuum field theory for the transition, which is characterized by an emergent global SO(3) symmetry and has four different formulations that are all related by dualities.

[1] Nature 571, 376 (2019).
[2] PRB 99, 165126 (2019).
[3] arXiv:1903.01992 [Nature Physics (2019)].