Date of Award

January 2013

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Physics & Astrophysics

First Advisor

Ju H Kim

Abstract

As a way to investigate the transport property of superconductor-insulator-superconductor (SIS) junction with two-gap superconductors such as MgB2 and iron superconductors, we study the microscopic structure of the Josephson current in a tunnel junction with a very narrow quasi-classical barrier. Also, the possibility of mid-gap states in two-gap superconductor is investigated, and their effects on the current-phase relation as well as the current density characteristics are studied. In the SIS break junction, mid-gap states appear at the Superconductor-Insulator interfaces due to an abrupt change in the superconducting order parameter, indicating that the two-gap superconductor SIS junction can yield a rich bound state structure in the energy gap. In this work, I study the mid-gap bound state energy of the two-gap superconductor-based short Josephson junctions. Also, I study the tunneling currents through the mid-gap states theoretically to estimate the effects of these bound states on the current-phase characteristics and the critical Josephson current.

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