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arXiv · 2207.01774

Hyperbolic fringe signal for twin impurity quasiparticle interference

Peize Ding·Tilman Schwemmer·Ching Hua Lee·Xianxin Wu·Ronny Thomale
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Abstract

We study the quasiparticle interference (QPI) pattern emanating from a pair of adjacent impurities on the surface of a gapped superconductor (SC). We find that hyperbolic fringes (HF) in the QPI signal can appear due to the loop contribution of the two-impurity scattering, where the location of the two impurities are the hyperbolic focus points. For a single pocket Fermiology, an HF pattern signals chiral SC order for non-magnetic impurities and requires magnetic impurities for non-chiral SC. For a multi-pocket scenario, a sign-changing order parameter such as $s_{\pm}$-wave likewise yields an HF signature. We discuss twin impurity QPI as a new tool to complement the analysis of superconducting order from local spectroscopy.

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Peize Ding, Tilman Schwemmer, Ching Hua Lee, Xianxin Wu, Ronny Thomale. 2022-07-05. Hyperbolic fringe signal for twin impurity quasiparticle interference. https://doi.org/10.1103/physrevlett.130.256001

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