Magnetic-field effects in the pseudogap phase: A competing energy gap scenario for precursor superconductivity

We study the sensitivity of T-c and the pseudogap onset temperature, T*, to low fields, H, using a BCS-based approach extended to arbitrary coupling. We find that T* and T-c which are of the same superconducting origin, have very different H dependences. This is due to the pseudogap, Delta (pg), which is present at the latter, but not former temperature. Our results for the coherence length xi fit well with existing experiments. We predict that very near the insulator xi will rapidly increase.