Realization of a hole-doped Mott insulator on a triangular silicon lattice

TL;DR

This paper demonstrates that a hole-doped Mott insulator can be realized on a silicon surface with a triangular lattice, exhibiting key Mott physics features similar to complex oxides, opening new avenues for quantum material engineering.

Contribution

The study introduces a silicon-based platform for Mott insulators with a triangular lattice, enabling exploration of exotic quantum phases in a more controllable and less complex material system.

Findings

Observation of spectral weight transfer indicating Mott physics

Formation of quasi-particle states at the Fermi level

Presence of a sharp density of states singularity

Abstract

The physics of doped Mott insulators is at the heart of some of the most exotic physical phenomena in materials research including insulator-metal transitions, colossal magneto-resistance, and high-temperature superconductivity in layered perovskite compounds. Advances in this field would greatly benefit from the availability of new material systems with similar richness of physical phenomena, but with fewer chemical and structural complications in comparison to oxides. Using scanning tunneling microscopy and spectroscopy, we show that such a system can be realized on a silicon platform. Adsorption of one-third monolayer of Sn atoms on a Si(111) surface produces a triangular surface lattice with half-filled dangling bond orbitals. Modulation hole-doping of these dangling bonds unveils clear hallmarks of Mott physics, such as spectral weight transfer and the formation of quasi-particle states at the Fermi level, well-defined Fermi contour segments, and a sharp singularity in the density of states. These observations are remarkably similar to those made in complex oxide materials, including high-temperature superconductors, but highly extraordinary within the realm of conventional sp-bonded semiconductor materials. It suggests that exotic quantum matter phases can be realized and engineered on silicon-based materials platforms.