Electronic procrystalline state in moire structures

TL;DR

This paper reports the experimental discovery of an electronic procrystalline state in a moire superstructure, revealing a new form of long-range ordered yet locally disordered electronic phase with tunable properties.

Contribution

It introduces the first observation of an electronic procrystalline state in a moire structure, demonstrating its coexistence with superconductivity and tunability via layer thickness.

Findings

Observation of long-range periodic charge modulation at moire scale.

Presence of short-range irregular charge orders within moire cells.

Coexistence of EPC state with superconductivity and tunability with layer thickness.

Abstract

Solid state materials can display varieties of atomic structural orders ranging from crystalline to amorphous, underlying their properties and diverse functionalities. Procrystal has emerged as a new category of solids, featuring a long-range ordered lattice framework tiled with disordered atomic or molecular structures on the lattice sites, arousing great interest due to its novel structural and physical properties. However, the electronic analogue of a procrystal, dubbed as an electronic procrystalline (EPC) state, has never been experimentally observed. Here, we report the observation of an EPC state in a moire superstructure formed between a monolayer metallic NiTe2 and a superconductor NbSe2 with incommensurate lattice wavevectors. The observed EPC state exhibits a long-range periodic charge modulation at the moire scale inlaid with short-range irregular orders within each moire cell. Strikingly, the short-range charge orders inside the moire unit cells have proximately root3*root3 quasi-period, which is absent in pristine NiTe2. Intriguingly, the EPC order is also observed in the superconducting state of the moire superstructure. Furthermore, the emergent EPC state and short-range charge order, coexisting with the proximity induced superconductivity, can be precisely modulated with the thickness of NiTe2. Our findings uncover the potential of moire platform for understanding and tuning novel correlated quantum phases with this exotic procrystalline order.