Thermal Hall conductance and a relative topological invariant of gapped two-dimensional systems

May 15, 2019
19 pages
Published in:
  • Phys.Rev.B 101 (2020) 4, 045137
  • Published: Feb 1, 2020
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Abstract: (APS)
We derive a Kubo-like formula for the thermal Hall conductance of a 2d lattice systems which is free from ambiguities associated with the definition of energy magnetization. We use it to define a relative topological invariant of gapped 2d lattice systems at zero temperature. Up to a numerical factor, it can be identified with the difference of chiral central charges for the corresponding edge modes. This establishes the bulk-boundary correspondence for the chiral central charge. We also show that for any local commuting projector Hamiltonian, the relative chiral central charge vanishes, while for free fermionic systems, it is related to the zero-temperature electric Hall conductance via the Wiedemann-Franz law.
Note:
  • 39 pages. v2: references and clarifications added, typos and some signs corrected. v3: a substantially revised version, the main results are unchanged. v4: paper re-written to make it more accessible and readable
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