Abstract
We argue that superconductivity in the coexistence region with spin-density-wave (SDW) order in weakly doped Fe pnictides erdiffers qualitatively from the ordinary state outside the coexistence region as it develops an additional gap component which is a mixture of intrapocket singlet () and interpocket spin-triplet pairings (the state). The coupling constant for the channel is proportional to the SDW order and involves interactions that do not contribute to superconductivity outside of the SDW region. We argue that the - and -type superconducting orders coexist at low temperatures, and the relative phase between the two is, in general, different from 0 or , manifesting explicitly the breaking of the time-reversal symmetry promoted by long-range SDW order. We argue that time reversal may get broken even before true superconductivity develops.
- Received 27 May 2014
DOI:https://doi.org/10.1103/PhysRevLett.113.167001
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