NANO-SCALE ELECTRON-ENERGY-LOSS SPECTROSCOPY OF THE OXYGEN K-EDGE IN BI2SR2CA1CU2O8+DELTA

We demonstrate, for the first time, that even in highly anisotropic, quasi-two-dimensional Bi2Sr2Ca1Cu2O8+delta, electron energy-loss spectroscopy (EELS) performed in a transmission electron microscope (TEM) is a very valuable technique for understanding local changes in the oxygen-hole density on a nanometer scale. After optimizing both the scattering angle of the incident beam and the collection angle of the spectrometer for a particular crystal orientation, a TEM-EELS experiment is capable of documenting local (similar to several nm) variations in strength of the pre-peak of oxygen absorption K edge spectrum. This investigation reveals the hole-concentration profile across grain boundaries, and hence, furthers understanding of the superconducting behavior of the grain boundary in this technologically important material.