A tunable and unidirectional one-dimensional electronic system Nb2n+1SinTe4n+2

Zhen Zhu,Nan Xu,Xu Yang,Dan-Dan Guan,Shiyong Wang,Zhi-Qiang Mao,Meng Yang,Yao-Yi Li,Hao-Ke Xu,Xiao-Ang Nie,Yugui Yao,Hao Zheng,You-Guo Shi,Canhua Liu,Si Li,Shengyuan A Yang,Jin-Feng Jia

doi:10.1038/s41535-020-0238-0

Abstract

One dimensional (1D) electronic system is a versatile platform hosting novel physics, such as charge density wave, Su-Schrieffer-Heeger (SSH) topological state and solitons, Tomonaga-Luttinger Liquid etc. Here, we systematically study the surface electronic properties on layered composition-tunable compounds Nb2n+1SinTe4n+2 (n = 1–5), which is predicted to be a nodal-line semimetal when n = 1 (Nb3SiTe6). Via scanning tunneling microscopy/spectroscopy, we observe 1D chains formed on the surface of the compounds. We uncover that with the increasing of n, the distance between the chains becomes larger, and the 1D electronic state is developed in the compounds with n ≥ 3. Our first-principle calculations reveal that the nodal-line in Nb3SiTe6 and the 1D electronic state in the crystals with higher n in fact arise from the same bands, which are protected by the same nonsymmorphic symmetry. Furthermore, we can understand the evolution of the electronic states on these series of compounds with such complicated structures and compositions based on a simple SSH type picture. Our experiment demonstrates a tunable and unidirectional 1D electronic system, which offers a concrete platform for the exploration of intriguing 1D electron physics and will enrich the opportunity for future condensed matter physics, material science and nanotechnology researches.

Highlights

When electrons are confined into a one-dimensional (1D) wire, many fundamentally important phenomena may emerge
On Nb3SiTe6 (n = 1), we focus on a segment on a bright chain (c chain) between two point defects, 1234567890():,; Fig. 1 Structural and spectroscopic properties of Nb2n+1SinTe4n+2 (n = 1–5). a Sketches of the monolayer Nb2n+1SinTe4n+2 compounds, which can be constructed by three building blocks
We have identified that the β bands are originated from c chains, while γ and δ bands are located on the b and c chains

Summary

INTRODUCTION

When electrons are confined into a one-dimensional (1D) wire, many fundamentally important phenomena may emerge. We show that the low-energy electrons in these materials are confined in 1D chain-like structures and are gapless ensured by a nonsymmorphic crystal symmetry. Because these chains are intrinsic component of the crystal lattice, they share a fixed orientation. The 1D confinement can be readily tuned by changing n, which plays the role of spacing between neighboring chains in this context As such, it overcomes the longstanding uniformity and tunability issues in realizing 1D electronic systems. The thermal and air stability natures of these materials will facilitate the future applications in 1D electronics

RESULTS

METHODS