Singularity of the London Penetration Depth at Quantum Critical Points in Superconductors

Debanjan Chowdhury,Subir Sachdev,Erez Berg,Brian Swingle

doi:10.1103/physrevlett.111.157004

Debanjan Chowdhury, Subir Sachdev + Show 2 more

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https://doi.org/10.1103/physrevlett.111.157004

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Abstract

We present a general theory of the singularity in the London penetration depth at symmetry-breaking and topological quantum critical points within a superconducting phase. While the critical exponents and ratios of amplitudes on the two sides of the transition are universal, an overall sign depends upon the interplay between the critical theory and the underlying Fermi surface. We determine these features for critical points to spin density wave and nematic ordering, and for a topological transition between a superconductor with Z2 fractionalization and a conventional superconductor. We note implications for recent measurements of the London penetration depth in BaFe2(As(1-x)P(x))2 [K. Hashimoto et al., Science 336, 1554 (2012)].

Highlights

We present a general theory of the singularity in the London penetration depth at symmetry-breaking and topological quantum critical points within a superconducting phase
The phase diagrams of the iron-based superconductors show a clear overlap between the spin density wave (SDW) and superconducting phases [7], and Hashimoto et al [8] have recently provided a careful study of the SDW quantum critical point in BaFe2(As1 xPx
We provide a general theory of the singularity in the superfluid sti↵ness and the London penetration depth near a wide class of symmetry-breaking or topological transitions within superconductors in two spatial dimensions

Summary

Introduction

We present a general theory of the singularity in the London penetration depth at symmetry-breaking and topological quantum critical points within a superconducting phase. An important focus of the study of the cuprate high temperature superconductors has been the quantum criticality of the onset of spin density wave (SDW) order within the superconducting phase.

Results

Conclusion