Possibility of a new type of mixed state in high-temperature superconductors

Both the temperature T and magnetic field H above some critical value destroy the superconducting state. The mixed state of a type-II superconductor makes it possible to sustain superconductivity in fields exceeding the thermodynamic critical field Hc. We hypothesize the possibility of a new type of mixed state, present even in the absence of a magnetic field, which would allow superconductivity to exist at temperatures much higher than the critical temperature Tc allowed by the conventional BCS theory. © 1990 The American Physical Society.