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<p>In the kagome superconductors <i>A</i>V<sub>3</sub>Sb<sub>5</sub> (<i>A</i>=Cs,Rb,K), a cascade of correlated electron phases cause exotic symmetry-breaking quantum states. In particular, the dissipationless chiral loop-current phase has been attracting increasing attention. A crucial clue is offered by the chirality of the quasiparticle interference signal observed in scanning tunneling microscopy. However, the connection between loop-current chirality and quasiparticle interference chirality remains poorly understood. Here, we reveal theoretically that a pronounced chiral quasiparticle interference signal emerges in the extremely dilute impurity regime (&#xa0;≲&#xa0;0.1%). A single impurity at site Z induces a quasiparticle interference chirality <i>χ</i><sub>Z</sub>&#xa0;=&#xa0;±&#xa0;1, determined by the direction of the <i>Z</i><sub>3</sub> nematicity, itself set by the relative position of the loop-current order in the star-of-David charge-density-wave phase. Notably, even a small magnetic field can smoothly switch the chirality, leading to field-induced shear lattice strain consistent with recent experiments. Our theoretical study provide key insights into the nature of the loop-current-induced symmetry-breaking states in kagome metals.</p>

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Origin of switchable quasiparticle-interference chirality in loop-current phase of kagome metals measured by scanning-tunneling-microscopy

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年10月29日

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  • Seigo Nakazawa,
  • Rina Tazai,
  • Youichi Yamakawa,
  • Seiichiro Onari,
  • Hiroshi Kontani

摘要

In the kagome superconductors AV3Sb5 (A=Cs,Rb,K), a cascade of correlated electron phases cause exotic symmetry-breaking quantum states. In particular, the dissipationless chiral loop-current phase has been attracting increasing attention. A crucial clue is offered by the chirality of the quasiparticle interference signal observed in scanning tunneling microscopy. However, the connection between loop-current chirality and quasiparticle interference chirality remains poorly understood. Here, we reveal theoretically that a pronounced chiral quasiparticle interference signal emerges in the extremely dilute impurity regime ( ≲ 0.1%). A single impurity at site Z induces a quasiparticle interference chirality χZ = ± 1, determined by the direction of the Z3 nematicity, itself set by the relative position of the loop-current order in the star-of-David charge-density-wave phase. Notably, even a small magnetic field can smoothly switch the chirality, leading to field-induced shear lattice strain consistent with recent experiments. Our theoretical study provide key insights into the nature of the loop-current-induced symmetry-breaking states in kagome metals.