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arXiv · 2410.20944

High-order van Hove singularities and nematic instability in the kagome superconductor CsTi$_3$Bi$_5$

Bikash Patra·Amrita Mukherjee·Bahadur Singh
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Abstract

ATi$_3$Bi$_5$ (A = Cs or Rb) are emerging topological kagome metals that exhibit superconductivity and nematicity without intertwining translational symmetry-breaking charge orders. In this work, we explore the fermiology of their titanium kagome electrons and identify a set of sublattice-pure, high-order van Hove singularities (VHSs) that can suppress charge ordering and enhance electronic correlations and superconductivity. Our calculations of charge susceptibility for kagome bands with both normal and high-order VHSs emphasize the role of these VHSs in driving electronic nematicity in CsTi$_3$Bi$_5$. Additionally, we compute the phonon spectrum and electron-phonon interactions for CsTi$_3$Bi$_5$ under pristine, doped, and kagome-exposed surface conditions, revealing its robustness against structural instabilities while enhancing the superconducting transition temperature. Our work positions ATi$_3$Bi$_5$ as a key platform for investigating superconductivity and electronic nematicity without translational symmetry-breaking states in kagome metals.

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Bikash Patra, Amrita Mukherjee, Bahadur Singh. 2024-10-28. High-order van Hove singularities and nematic instability in the kagome superconductor CsTi$_3$Bi$_5$. https://doi.org/10.1103/physrevb.111.045135

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