Unconventional thermoelectric effect in superconductors that break time-reversal symmetry

We demonstrate that superconductors that break time-reversal symmetry can exhibit thermoelectric properties, which are entirely different from the Ginzburg mechanism. As an example, we show that in the s + is superconducting state there is a reversible contribution to thermally induced supercurrent, whose direction is not invariant under time-reversal operation. Moreover in contrast to Ginzburg mechanism it has a singular behavior near the time-reversal symmetry breaking phase transition. The effect can be used to confirm or rule out the s + is state, which is widely expected to be realized in pnictide compounds Ba1-xKxFe2As2 and stoichiometric LiFeAs.