Doping Dependencies of Onset Temperatures for the Pseudogap and Superconductive Fluctuation in Bi2Sr2CaCu2O8+delta, Studied from Both In-Plane and Out-of-Plane Magnetoresistance Measurements

作者：Usui Tomohiro^*; Fujiwara Daiki; Adachi Shintaro; Kudo Hironobu; Murata Kosuke; Kushibiki Haruki; Watanabe Takao; Kudo Kazutaka; Nishizaki Terukazu; Kobayashi Norio; Kimura Shojiro; Yamada Kazuyoshi; Naito Tomoyuki; Noji Takashi; Koike Yoji

来源：Journal of the Physical Society of Japan, 2014, 83(6): 064713.

DOI：10.7566/JPSJ.83.064713

To investigate the relationship between the pseudogap and superconductivity, we measured both the in-plane (rho(ab)) and out-of-plane (rho(c)) resistivity for oxygen-controlled Bi2Sr2CaCu2O8+delta single crystals subject to magnetic fields (parallel to the c-axis) of up to 17.5 T. The onset temperature for the superconductive fluctuation, T-scf, is determined by the large positive in-plane magnetoresistance (MR) and negative out-of-plane MR observed near T-c, whereas the pseudogap opening temperature T* is determined by the semiconductive upturn of the zero-field rho(c). T-scf was found to scale roughly as T-c, with a decreasing temperature interval between them upon doping. On the other hand, T* starts out much higher than T-scf but decreases monotonically upon doping; finally, at a heavily overdoped state, it is not observed above T-scf. These results imply that the pseudogap is not a simple precursor of superconductivity, but that further study is needed to determine whether or not T* exists below T-scf in the heavily overdoped state.

• 出版日期2014-6