Unquantized thermal Hall effect in quantum spin liquids with spinon Fermi surfaces

Abstract

Recent theoretical studies have found quantum spin-liquid states with spinon Fermi surfaces upon the application of a magnetic field on a gapped state with topological order. We investigate the thermal Hall conductivity across this transition, describing how the quantized thermal Hall conductivity of the gapped state changes to an unquantized thermal Hall conductivity in the gapless spinon Fermi surface state. We consider two cases, both of potential experimental interest: the state with non-Abelian Ising topological order on the honeycomb lattice and the state with Abelian chiral spin-liquid topological order on the triangular lattice.

Giant phonon anomalies in the proximate Kitaev quantum spin liquid α-RuCl3

“…2 , the P 2 phonon energy is the same as the magnon energy near the M point 19 , 21 , 38 . Interestingly, the P 2 phonon intensity at the M point is enhanced at 10 K~ T N , supporting magnon–phonon coupling 46 . In addition, strong anharmonicity is proposed in the magnon excitation of this material 47 , which represents the break-down of the spin quasiparticles.…”

Planar thermal Hall effect of topological bosons in the Kitaev magnet α-RuCl3

“…Crucially, the reversal of Ω induced by reversing B leads to an Onsager planar thermal Hall current.If the excitations are fermions, Eq. 1 yields the (T -independent) Kane-Fisher result[28,29]…”

Modular commutator in gapped quantum many-body systems

“…It will be interesting to calculate the modular commutator in other systems that have a chiral nature. Notable candidates are: (1) the critical point of the quantum phase transition between a pair of gapped chiral phases; (2) gapless systems (with a non-quantized) thermal Hall response, e.g., those proposed to be described by a chiral spin liquid with spinon Fermi surfaces [55,56]; and (3) freefermion systems, which may admit a simple form of the quantity [57]. Another interesting example is the Standard model of particle physics, which is a chiral theory; precisely speaking, it violates both parity P [58,59] and time reversal T (which is better known as CP violation) [60][61][62].…”