Existence of Pseudogap at the Transition Temperature of an Electron-Doped Copper-Oxide Superconductor

We present the scanning tunnelling spectroscopy (STS) studies of the energy gap (Delta) at the Fermi surface of electron-doped high-temperature (high-T-c) cuprate superconductor Pr0(88LaCe0(12CuO4-delta, which is commonly known as PLCCO. We found that the energy gap does not vanish at the transition temperature (T-c). Moreover, it was observed that gap-like features are present at some locations of the sample at temperatures above T-c. The energy gap with magnitude is found consistent with d-wave symmetry. We also found the value of the ratio 2 Delta)KBTc higher than 7, which puts electron-doped cuprates in strong coupling regime.