Coexistence of stripe order and superconductivity in NaAlSi

TL;DR

This study uses scanning tunneling microscopy to reveal the coexistence of stripe charge order and s-wave superconductivity in NaAlSi, showing their spatial interplay and potential static nature.

Contribution

It provides the first direct observation of stripe order coexisting with superconductivity in NaAlSi, highlighting their interaction at the atomic scale.

Findings

Stripe order manifests as a unidirectional charge modulation with a four-lattice-period.

The charge modulation exhibits a phase shift under opposite bias voltages.

Stripe order modulates the superconducting coherence peaks.

Abstract

Here, we report a scanning tunneling microscopy study on an s-wave superconductor NaAlSi, revealing the coexistence of stripe order and superconductivity. This stripe order manifests as a unidirectional spatial charge modulation with a commensurate period of four times the lattice constant. This modulation undergoes a phase shift in the differential conductance maps under opposite bias voltages, while its period remains approximately constant over an energy range of $\pm$50 meV. These features suggest that this stripe is likely a static charge order. Furthermore, we find that the stripe order imposes a periodic modulation on the intensity of the superconducting coherence peaks. This work provides new perspectives on the intricate interplay between stripe order and s-wave superconductivity.