Giant thermal Hall conductivity from neutral excitations in the pseudogap phase of cuprates

Understand

The nature of the pseudogap phase of cuprates remains a major puzzle.

• Although there are indications that this phase breaks various symmetries, there is no consensus on its fundamental nature.
• Although Fermi-surface, transport and thermodynamic signatures of the pseudogap phase are reminiscent of a transition into a phase with antiferromagnetic order, there is no evidence for an associated long-range magnetic order.
• Here we report measurements of the thermal Hall conductivity $\kappa_{\rm xy}$ in the normal state of four different cuprates (Nd-LSCO, Eu-LSCO, LSCO, and Bi2201) and show that a large negative $\kappa_{\rm xy}$ signal is a property of the pseudogap phase, appearing with the onset of that phase at the critical doping $p^*$.