Local tunneling spectroscopy of the electron-doped cuprate superconductorSm1.85Ce0.15CuO4

Abstract

We present local tunneling spectroscopy in the optimally electron-doped cuprate ${\mathrm{Sm}}_{2\ensuremath{-}x}{\mathrm{Ce}}_{x}\mathrm{Cu}{\mathrm{O}}_{4}$, $x=0.15$. A clear signature of the superconducting gap is observed with an amplitude ranging from place to place and from sample to sample ($\ensuremath{\Delta}\ensuremath{\sim}3.5--6\phantom{\rule{0.3em}{0ex}}\mathrm{meV})$. Another spectroscopic feature is simultaneously observed at high energy with an amplitude ranging from $\ifmmode\pm\else\textpm\fi{}60$ to $\ifmmode\pm\else\textpm\fi{}80\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$. Its energy scale and temperature evolution are found to be compatible with previous photoemission and optical experiments. If interpreted as the signature of antiferromagnetic order in the samples, these results could suggest the coexistence on the local scale of antiferromagnetism and superconductivity on the electron-doped side of cuprate superconductors.