Robust superconductivity intertwined with charge density wave and disorder in Pd-intercalated ErTe$_3$

TL;DR

This study reveals that in Pd-intercalated ErTe3, superconductivity coexists with charge density wave order without competition, even amid disorder and short-range CDW persistence, challenging traditional views.

Contribution

It demonstrates the coexistence of superconductivity and CDW in ErTe3 with no direct competition, despite disorder and short-range CDW, providing new insights into intertwined orders.

Findings

Superconductivity and CDW coexist over most of the intercalation range.

Superconductivity is insensitive to local defects in CDWs.

Vestiges of Fermi-level distortions influence the superconducting state.

Abstract

Pd-intercalated ErTe$_3$ is studied as a model system to explore the effect of "intertwined" superconducting and charge density wave (CDW) orders. Despite the common wisdom that superconductivity emerges only when CDW is suppressed, we present data from STM and AC susceptibility measurements that show no direct competition between CDW order and superconductivity. Both coexist over most of the intercalation range, with uniform superconductivity over length scales that exceed the superconducting coherence length. This is despite persisting short-range CDW order and increased scattering from the Pd intercalation. While superconductivity is insensitive to local defects in either of the bi-directional CDWs, vestiges of the Fermi-level distortions are observed in the properties of the superconducting state.