Quantum anomalous Hall effect from intertwined moiré bands.

Area of Science:

• Condensed matter physics
• Semiconductor physics
• Materials science

Background:

• Electron correlation and band topology are key areas in modern physics.
• Semiconductor moiré materials offer a tunable platform for studying electron correlation phenomena.
• Non-trivial band topology in these systems remains largely unexplored.

Purpose of the Study:

• To investigate the interplay of electron correlation and band topology in semiconductor moiré materials.
• To explore the possibility of observing topological phenomena like the quantum anomalous Hall effect.
• To understand electric-field-induced topological phase transitions.

Main Methods:

• Fabrication and characterization of AB-stacked MoTe2/WSe2 moiré heterobilayers.
• Application of out-of-plane electric fields to tune material properties.
• Measurement of Hall resistance and longitudinal resistance under varying conditions.

Main Results:

• Observation of the quantum anomalous Hall effect (quantized Hall resistance h/e^2) in AB-stacked MoTe2/WSe2 moiré heterobilayers.
• Demonstration that electric fields control both bandwidth and band topology.
• Identification of an electric-field-induced topological phase transition from Mott insulator to quantum anomalous Hall insulator, preceding an insulator-to-metal transition without bulk charge gap closure.

Conclusions:

• Semiconductor moiré heterobilayers are promising platforms for exploring correlated topological states.
• Electric-field-tunable band topology offers new pathways for controlling quantum phenomena.
• The observed phase transition mechanism provides insights into novel topological phenomena driven by correlation and topology.