Single crystals of Bi2Sr2CaCu2Ox with transition temperatures of 85 K have been studied using a low temperature scanning tunneling microscope. Spectra of very weakly coupled point contact configuration have been obtained and reproducible periodic conductance structures in the bias voltage have been found. A model based on geometrical resonances in superconducting superlattice is proposed and found to provide a satisfactory explanation of the data.
Bibliographical noteFunding Information:
The density of states of a superlattice can be written in the following form (4): * Supported in part by the National Science Foundation under Grant NSF/DMR-8908094. + Present address: Shell Development Company, 3737 Belaire Blvd., Houston, TX 77025