Fabrication and Anisotropic Transport Properties of (Hg, Re)Ba_2CaCU_2O_y Epitaxial Thin Films on Vicinal Substrates with Buffer Layers

摘要

Approximately 160-nm-thick (Hg_(0.9)Re_(0.1))Ba_2CaCu_2O_y ((Hg, Re)-1212) thin films were fabricated on SrTiO_3 (STO) vicinal substrates with the tilt angle of 5-18.4°. By employing Y_(0.9)La_(0.2)Ba_(1.9)Cu_3O_y, or Pr_(1.4)Ba_(1.6)Cu_3O_y thin films as buffer layers on the STO vicinal substrates, single-phase (Hg,Re)-1212 films with the c-axis normal to STO (001) and a Tc of 115-117 K were successfully grown for all the tilt angles. It was confirmed that the crystallinity of the vicinal films was comparable to that for conventional films on STO (001) substrates. The c-axis resistivity estimated from their anisotropic transport properties clearly exhibited semiconductor-like behavior below 180 K, which is similar to the case for optimally-doped Bi_2Sr_2CaCu_2O_y (Bi-2212), though the resistivity anisotropy of approximately 1000 is about one order of magnitude smaller than that of Bi-2212. Moreover, multiple branch structures characteristic of intrinsic Josephson junctions were observed in the current-voltage curves in the direction across their a-b planes.