Superconductivity in two-dimensional disordered Dirac semimetals

Jing Wang, Peng-Lu Zhao, Jing-Rong Wang, and Guo-Zhu Liu
Phys. Rev. B 95, 054507 – Published 15 February 2017

Abstract

In two-dimensional Dirac semimetals, Cooper pairing instability occurs only when the attractive interaction strength |u| is larger than some critical value |uc| because the density of states vanishes at Dirac points. Disorders enhance the low-energy density of states but meanwhile shorten the lifetime of fermions, which tend to promote and suppress superconductivity, respectively. To determine which of the two competing effects wins, we study the interplay of Cooper pairing interaction and disorder scattering by means of renormalization group method. We consider three types of disorders, including random mass, random gauge potential, and random chemical potential, and show that the first two suppress superconductivity. In particular, the critical BCS coupling |uc| is increased to certain larger value if the system contains only random mass or random gauge potential, which makes the onset of superconductivity more difficult. In the case of random chemical potential, the effective disorder parameter flows to the strong coupling regime, where the perturbation expansion breaks down and cannot provide a clear answer concerning the fate of superconductivity. When different types of disorder coexist in one system, their strength parameters all flow to strong couplings. In the strong coupling regime, the perturbative renormalization group method becomes invalid, and one needs to employ other methods to treat the disorder effects. We perform a simple gap equation analysis of the impact of random chemical potential on superconductivity by using the Abrikosov-Gorkov diagrammatic approach, and also briefly discuss the possible generalization of this approach.

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  • Received 22 April 2016
  • Revised 25 January 2017

DOI:https://doi.org/10.1103/PhysRevB.95.054507

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Jing Wang1, Peng-Lu Zhao1, Jing-Rong Wang2, and Guo-Zhu Liu1,*

  • 1Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
  • 2High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, P. R. China

  • *Corresponding author: gzliu@ustc.edu.cn

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Issue

Vol. 95, Iss. 5 — 1 February 2017

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