Direct identification of superconducting regions in an inhomogeneous specimen by electron shadow microscopy

Abstract

Scanning and transmission electron microscopy have played a major part in evaluating the microstructure of the new high-temperature superconductors. Complex fabrication routes have led to a wide variety of phases in the samples produced, and the high-temperature superconductor itself has a complex microstructure on which its superconducting properties are dependent. Finally, the process of preparing specimens for examination by electron microscopy can itself lead to degradation of the superconducting properties. As a result it is desirable to establish directly that the regions studied are indeed superconducting, and to relate the superconducting properties to the local microstructure. Here we describe a convenient method for performing such an evaluation. One possible method, which relies on image contrast in a scanning electron microscope, was recently proposed¹. Another, which we discuss here, involves the use of a long established, if little used, technique of electron shadow microscopy².