Direct observation of intrinsic Josephson junction characteristics in electron-doped Sm2-xCexCuO4-delta

摘要: We have investigated the current-voltage $(CV)$ characteristics of intrinsic Josephson junctions (IJJs) in electron-doped high-${T}_{c}$ superconductor ${\mathrm{Sm}}_{2\ensuremath{-}x}{\mathrm{Ce}}_{x}\mathrm{Cu}{\mathrm{O}}_{4\ensuremath{-}\ensuremath{\delta}}$ by using a small mesa structure fabricated on single crystal surface. It is found that multiple resistive branches, i.e., typical IJJ characteristics, are observed $CV$ when junction area $10\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}{\mathrm{m}}^{2}$ or less. also critical current density ${J}_{c}$ $7.5\phantom{\rule{0.3em}{0ex}}\mathrm{kA}∕{\mathrm{cm}}^{2}$ at $4.2\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ for ${T}_{c}=20.7\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The penetration depth experimentally estimated to be $1.0--1.6\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{m}$ from size dependence ${J}_{c}$. Both and ${T}_{c}$ decrease with carrier doping level, as hole-doped ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}\mathrm{Ca}{\mathrm{Cu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ heavily overdoped region. These results discussed relation locking terms coupled stack model.