Scanning Tunneling Microscopy/Spectroscopy of Heavily Overdoped Bi_(2)Sr_(2)CuO_(y) Single Crystals

摘要

We have carried out scanning tunneling microscopy/spectroscopy (STM/STS) of heavily overdoped Bi_(2)Sr_(2)CuO_(y) single crystals with T_(c)<2 K. STS spectra showed a pseudogap structure with dull coherence peaks. Furthermore, we found that the magnitude of pseudogap is spatially non-uniform in a nm scale and varies from 10 to 30 meV. This supports a scenario that the electronic inhomogeneity is a consequence of randomly distributed Coulomb potential in the CuO_(2) layers induced by disorder of excess oxygen in the BiO layers.