Anisotropy of electronic structure and spectral excitations in oxide superconductors via low loss EELS

Abstract

The low loss (i.e. the valence band) portion of transmission electron energy loss spectroscopy (EELS) spectrum comprises of very high signal (as well as high signal to noise ratio for many excitations) with rich information embedded in it about electronic and optical properties of solids. There are, however, clear interpretation problems in low loss EELS owing to the complexity of electronic transitions in multi-component systems (e.g. high Tc oxides) and the perennial multiple scattering which masks real information, and considerable deconvolution (often dicy) is necessary before useful information can be obtained. This paper briefly reviews the relevant aspects of low loss EELS in the context of electronic structure and spectral excitations in oxide superconductors. Particular attention is paid to the details of various corrections and deconvolution procedures, illustrated with examples of oxide superconductors. It is shown that a prudent combination of careful experiments, appropriate deconvolution procedures and conservative interpretation are key to successful application of this technique. This review argues that low loss EELS is a viable technique even for complex oxides as in superconductors.