Significant thermal Hall effect in the 3d cobalt Kitaev system Na2Co2TeO6

Abstract

Kitaev physics has recently attracted attention in condensed matter for its anticipated quantum spin liquid (QSL) state. The thermal transport measurement is crucial for probing the features of charge-neutral quasiparticles. In this letter, we report a significant thermal Hall effect in Na2Co2TeO6 (NCTO), a Kitaev QSL candidate, when the magnetic field is applied along the out-of-plane direction of the honeycomb plane. The thermal conductivity (κxx ) and thermal Hall conductivity (κxy) in NCTO reveal distinct magnetic field dependences below and above the Neel temperature (TN ) of 27 K. For T > TN, κxx has a monotonic decrease in the field dependence, while κxy persists up to T ∗ = 150 K. On the other hand, both κxx and κxy exhibit complex field dependence for T < TN.