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Order parameter symmetry and mode coupling effects at dirty superconducting quantum phase transitions

Rastko Sknepnek·Thomas Vojta·Rajesh Narayanan
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Abstract

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.

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Rastko Sknepnek, Thomas Vojta, Rajesh Narayanan. 2004-09-27. Order parameter symmetry and mode coupling effects at dirty superconducting quantum phase transitions. https://doi.org/10.1103/physrevb.70.104514

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