Anomalous superfluid density in quantum critical superconductors

Kenichiro Hashimoto, Yuta Mizukami, Ryo Katsumata, Hiroaki Shishido, Minoru Yamashita, Hiroaki Ikeda, Yuji Matsuda, John A. Schlueter, Jonathan D. Fletcher, Antony Carrington, Daniel Gnida, Dariusz Kaczorowski, Takasada Shibauchi*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

21 Citations (Scopus)

Abstract

When a second-order magnetic phase transition is tuned to zero temperature by a nonthermal parameter, quantum fluctuations are critically enhanced, often leading to the emergence of unconventional superconductivity. In these "quantum critical" superconductors it has been widely reported that the normal-state properties above the superconducting transition temperature T-c often exhibit anomalous non-Fermi liquid behaviors and enhanced electron correlations. However, the effect of these strong critical fluctuations on the superconducting condensate below Tc is less well established. Here we report measurements of the magnetic penetration depth in heavy-fermion, iron-pnictide, and organic superconductors located close to antiferromagnetic quantum critical points, showing that the superfluid density in these nodal superconductors universally exhibits, unlike the expected T-linear dependence, an anomalous 3/2 power-law temperature dependence over a wide temperature range. We propose that this noninteger power law can be explained if a strong renormalization of effective Fermi velocity due to quantum fluctuations occurs only for momenta k close to the nodes in the superconducting energy gap A(k). We suggest that such "nodal criticality" may have an impact on low-energy properties of quantum critical superconductors.

Original languageEnglish
Pages (from-to)3293-3297
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume110
Issue number9
DOIs
Publication statusPublished - 26 Feb 2013

Keywords

  • CECOIN5
  • mass enhancement
  • SCATTERING
  • HEAVY-FERMION SUPERCONDUCTIVITY
  • METALS
  • LIQUID
  • T-C
  • d-wave superconductivity
  • spin fluctuations
  • TEMPERATURE PENETRATION DEPTH
  • quasiparticle scattering
  • superfluid stiffness

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