Role of superconducting fitness in pairing from fluctuating order

Unconventional superconductivity is often observed near other ordered states. Although fluctuations of the ordered state are believed to mediate a pairing interaction, a general principle relating the ordered state to the pairing symmetry is lacking. Here, the authors analyze the pairing interaction from a general fluctuating order and develop a simple heuristic test to determine whether a given pairing channel is attractive or repulsive. This is based on a well-known measure of the compatibility of the ordered and pairing states.