University of Minnesota
School of Physics & Astronomy

Condensed Matter Seminar

Wednesday, October 21st 2015
1:25 pm:
Speaker: Jian Kang - University of Minnesota
Subject: Robustness of quantum critical pairing aginst disorder

Unconventional superconductivity is found in close proximity to a putative magnetic quantum critical point in several materials, such as heavy fermions, organics, cuprates, and iron pnictides. This led to the proposal that, in contrast to conventional electron-phonon superconductors, critical magnetic fluctuations promote the binding of the electrons in Cooper pairs. Experiments in many of these materials revealed that their superconducting transition temperature Tc is remarkably robust against disorder, particularly when compared to the predictions from the conventional Abrikosov-Gor'kov theory of dirty superconductors. In this talk, we investigate the impact of weak impurity scattering on the onset of the pairing state mediated by quantum critical magnetic fluctuations.We find that both the build-up of incoherent electronic spectral weight near the magnetic quantum phase transition, as well as the changes in the pairing interaction caused by disorder, lead to a significant reduction in the suppression rate of Tc with disorder, as compared to the Abrikosov-Gor'kov theory. Both effects are unique to the problem of electronically-mediated pairing, shedding new light on the understanding of unconventional superconductivity in correlated materials, where disorder is always present.

Faculty Host: Rafael Fernandes

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