Thesis (Ph. D.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Dec. 31, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Department of Physics, University of Alberta." Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 92-100). Also available in print.

Thesis (M. Phil.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 59-61).

In this thesis, We will focus on discussing the Andreev tunneling and Josephson tunneling of underdoped cuprate superconductors. In particular, we emphasize how the pseudogap of the underdoped cuprate influences these tunneling behaviors. Our calculation is based on the theory of YRZ Green’s function in which the pseudogap acts as a precursor to the undoped Mott insulator. In the study of Andreev tunneling, the tunneling spectroscopy we obtained exhibits a two-gap feature, i. e., a small energy gap associated with Andreev reflection in the transparent limit and a large gap associated with single particle tunneling. Our results are in good agreement with the two-gap scenario observed in tunneling experiments for underdoped cuprate. In the study of Josephson tunneling, we aimed to test the proposal of “cooperon physics” by examining the Josephson coupling between two optimally doped (or overdoped) cuprate superconductors separated by a barrier of an underdoped-cuprate in its pseudogap state with finiteenergy cooperon excitation. Our calculation shows a significant contribution from the cooperon excitation to the Josephson coupling, which is comparable to that from nodal quasiparticles. Moreover, our results give a good description of the temperature-dependent enhanced Josephson tunneling revealed in experiments. / published_or_final_version / Physics / Doctoral / Doctor of Philosophy

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published_or_final_version / abstract / toc / Physics / Master / Master of Philosophy

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

published_or_final_version / Physics / Master / Master of Philosophy