Observation of local barrier height and electronic structure on cuprate superconductor by STM/STS

Sugimoto, Akira; Toshikazu, Ekino; Eisaki, Hiroshi Japan

Recently, the nanoscale-electronic inhomogeneity of cuprate superconductors that shows up as spatial modulation of gap amplitude has been revealed. However, at present, it is unclear whether the inhomogeneous electronic structure is related with the distribution of charge density or not. The local barrier height (LBH, i.e., local workfunction) is considered to contain the information of charge density and is also very important parameter for the measurement of tunnel spectrum. We have investigated the LBH of Bi₂Sr₂CaCu₂O_8+y (Bi2212, Tc=93K) superconducting single crystal using scanning tunneling microscopy / spectroscopy (STM/STS). It is found that the atomically resolved LBH distribution is strongly related with the well-known supermodulation structure of Bi2212 surface. However, the comparison with simultaneously obtained local density of state (LDOS) distribution shows that there are few correlations between the spatial modulation of gap amplitude and LBH.

---

back