One-Dimensional Metal Embedded in Two-Dimensional Semiconductor in Nb<sub>2</sub>Si<sub><i>x</i>–1</sub>Te<sub>4</sub>
Binbin Wang, Wei Xia, Si Li, K. Wang, Shengyuan A. Yang, Yanfeng Guo, Jiamin Xue
Abstract
The ternary van der Waals material Nb2Six–1Te4 demonstrates many interesting properties as the content of Si is changed, ranging from metallic Nb3SiTe6 (x = 5/3) to narrow-gap semiconductor Nb2SiTe4 (x = 2) and with the emergence of one-dimensional Dirac fermion excitations in between. An in-depth understanding of their properties with different stoichiometry is important. Here we use scanning tunneling microscopy and spectroscopy to reveal that Nb2Six–1Te4 is a system with spontaneously developed and self-aligned one-dimensional metallic chains embedded in a two-dimensional semiconductor. Electron quasiparticles form one- and two-dimensional standing waves side by side. This special microscopic structure results in strong transport anisotropy. Along the chain direction the material behaves like a metal, while perpendicular to the chain direction, it behaves like a semiconductor. These findings provide an important basis for further investigation of this intriguing system.