Drastic enhancement of the thermal Hall angle in a $d$-wave superconductor

Abstract

The drastic enhancement of the thermal Hall angle in d-wave superconductors was observed experimentally in cuprate superconductors and in CeCoIn5 at low temperatures and weak magnetic field. However, to the best of our knowledge, its microscopic calculation has not been performed yet. To study this microscopically, we derive the thermal Hall coefficient in extreme type-II superconductors with an isolated pinned vortex based on the augmented quasiclassical equations of superconductivity with the Lorentz force. Using it, we can confirm that the quasiparticle relaxation time and the thermal Hall angle are enhanced in d-wave superconductors without impurities of the resonant scattering because quasiparticles around the gap nodes which become dominant near zero temperature are restricted to the momentum in a specific orientation. This enhancement of the thermal Hall angle may also be observed in other nodal superconductors with large magnetic-penetration-depth.

Spontaneous thermal Hall conductance in superconductors with broken time-reversal symmetry

“…There has been strong interest in the thermal Hall coefficients, which have been discussed in magnetic systems [15][16][17][18] as well as superconductors in the vortex phase [19,20]. Recently, κ yx has received even more attention due to the search for anyonic and fractionalized excitations in condensed matter systems [21][22][23], where the quantized thermal Hall conductivity has been proposed as a method to detect the topologically protected edge states in fractional quantum Hall states [22,23], Kitaev magnets [21,24] or topological superconducting systems [22,[25][26][27].…”