Tunneling Microscopy and Spectroscopy of High Tc Superconductors and Mesoscopic Systems

摘要

The thesis discusses several aspects and applications of Scanning Tunneling Microscopy (STM). Chapter 2 shows that scanning tunneling microscopy is an extremely powerful technique. It can give topographical and spectroscopical information on sub-nanometer scale. Its imaging capacities are used in a broad range of scientific and technological applications. Chapter 3 discusses the microscopic and macroscopic structure of YBa2Cu3O(7-delta) crystals. Chapter 4 presents spectroscopic measurements on La(1.85)Sr(0.15)CuO4 and YBa2Cu3O(7-delta). The new class of high-T(c) superconductors appeared to have an energy gap and a density of states which is, within the experimental accuracy, consistent with the BCS theory. Chapter 5 discusses the possible presence of a Coulomb blockade in an STM geometry. Clear evidence of this process has been obtained. Chapter 6 described STM images of Au(55) and Pd(561) clusters deposited on gold and graphite substrates. The last chapter described a new UHV STM. The system has very promising features. It has a base pressure of about 1 x 10(sup -10)mbar and can evaporate a material like iron at a pressure of 3 x 10(sup -10)mbar.