Transport properties of chiral p-wave superconductor-normal metal nanostructures

Thesis (Ph.D.)--University of Washington, 2014In this thesis, we present a theory of electron transport for unconventional superconductors. We focus on the superconducting properties of Sr₂RuO₄, which is a strong candidate for two dimensional p-wave superconductivity in electronic systems. We present Green function formulation of the theory of superconductivity and reduce the formulation within quasiclassical approximation. To study the systems with disordered normal metal junctions, we derive the boundary conditions of quasiclassical equations from the microscopic theory considering a spin active boundary. Boundary between normal metal and superconductor is modeled with Rashba type spin orbit coupling. An exact solution of the resulting equations are given and the resistance of the model system is calculated as a function of temperature, boundary transparency and superconducting state symmetry. The developed theory is used to study the phase transition of unconventional superconductors with increasing impurity concentration. It has been shown that, in the strong disordered regime, system can be modeled as Mattis model known from the theory of spin glasses. We show that with increasing disorder there will be two consecutive phase transitions: A phase transition from unconventional superconductor to s-wave superconductor followed by a transition from s-wave superconductor to normal metal. A qualitative phase diagram is prsented and corrections to Mattis model approximation is considered