Microwave absorption spectrum and reentrant phase in Bi2212 single crystal: temperature dependence

Abstract

We measured non-resonant microwave absorption (NMA) under magnetic field ( H a) sweeps on Bi2212 single crystals at various temperatures T in order to elucidate the reentrant phase, which is a characteristic feature of two dimensional high temperature superconducting systems. NMA were measured at a low microwave power of 0.1 mW at 9.28 GHz with H a∥ c-axis. The NMA spectrum at 77.3 K shows only a sharp first peak near zero field. The spectrum evolves with increasing T, and at 80 K the spectrum shows the first peak followed by a dip and a broad second peak at higher fields. The first peak, the dip and the broad peak correspond to Meissner state, reentrant liquid-1 phase and solid phase, respectively. The dip and broad peak shift towards the lower fields with increasing T according to the reentrant phase diagram.