Order-Parameter Symmetry and Mode-Coupling Effects at Dirty Superconducting Quantum Phase Transitions

Rastko Sknepnek
Thomas Vojta, Missouri University of Science and Technology
Rajesh Narayanan

This document has been relocated to http://scholarsmine.mst.edu/phys_facwork/376

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We derive an order-parameter field theory for a quantum phase transition between a disordered metal and an exotic (non- s -wave) superconductor. Mode coupling effects between the order parameter and other fermionic soft modes lead to an effective long-range interaction between the anomalous density fluctuations which is reflected in singularities in the free energy functional. However, this long-range interaction is not strong enough to suppress disorder fluctuations. The asymptotic critical region is characterized by run-away flow to large disorder. For weak coupling, this asymptotic region is very narrow. It is preempted by a wide crossover regime with mean-field critical behavior and, in the p -wave case, logarithmic corrections to scaling in all dimensions.