Sliding two-dimensional superconductivity and charge-density-wave state in a bulk crystal

TL;DR

This study demonstrates that interlayer sliding in bulk 3R-NbSe2 can induce a 2D-like superconducting state with unconventional properties, revealing a new method to explore quantum phenomena in layered materials.

Contribution

The paper introduces interlayer sliding as a novel approach to induce and study 2D superconductivity and charge-density-wave states in bulk layered crystals.

Findings

Interlayer sliding suppresses interlayer coupling and mirror symmetry.

Stabilization of Ising-type superconductivity coexisting with unconventional CDW.

Superconducting state shows two-fold symmetry and competition between SOC types.

Abstract

Superconductivity in the two-dimensional (2D) limit is a fertile ground for exotic quantum phenomena-many of which remain elusive in their 3D counterparts. While studies of 2D superconductivity have predominantly focused on mono- or few-layer systems, we demonstrate an alternative route-interlayer sliding in bulk crystals. Through a precisely controlled growth strategy, we engineer interlayer sliding in bulk 3R-NbSe2, deliberately disrupting [001] mirror symmetry and drastically suppressing interlayer coupling. Remarkably, this structural manipulation stabilizes Ising-type superconductivity coexisting with an unconventional charge-density-wave (CDW) state akin to that of monolayer 2H-NbSe2. The sliding phase exhibits a pronounced suppression of the upper critical field at low temperatures, revealing a delicate competition between Ising and Rashba spin-orbit coupling (SOC) in the globally noncentrosymmetric lattice. Intriguingly, the superconducting state displays two-fold symmetry, a signature that may arise from asymmetric SOC or a multi-component pairing order parameter. Our work establishes interlayer sliding as a symmetry-breaking tool to promote 2D superconductivity in bulk materials-without resorting to extrinsic intercalation or doping. More broadly, this approach sets a paradigm for unlocking hidden quantum states in layered materials, offering a new dimension in design of quantum matter.