Nanoscale Conductivity Imaging of Correlated Electronic States in WSe2/WS2 Moir\'e Superlattices

TL;DR

This study uses microwave impedance microscopy to visualize correlated electronic states, including Mott insulators, in WSe2/WS2 moiré superlattices at nanoscale, revealing temperature stability and local inhomogeneities.

Contribution

First nanoscale imaging of correlated electronic states in WSe2/WS2 moiré superlattices, demonstrating the persistence of Mott insulating states and local disorder effects.

Findings

Observation of Mott insulator at one hole per moiré unit cell up to 150 K

Identification of a Mott insulator at one electron per moiré unit cell

Visualization of inhomogeneity indicating local disorder effects

Abstract

We report the nanoscale conductivity imaging of correlated electronic states in angle-aligned WSe2/WS2 heterostructures using microwave impedance microscopy. The noncontact microwave probe allows us to observe the Mott insulating state with one hole per moir\'e unit cell that persists for temperatures up to 150 K, consistent with other characterization techniques. In addition, we identify for the first time a Mott insulating state at one electron per moir\'e unit cell. Appreciable inhomogeneity of the correlated states is directly visualized in the hetero-bilayer region, indicative of local disorders in the moir\'e superlattice potential or electrostatic doping. Our work provides important insights on 2D moir\'e systems down to the microscopic level.