Optical Signatures of -1/3 Fractional Quantum Anomalous Hall State in Twisted MoTe_{2}

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Topological Phases of Matter

Background:

• Strongly correlated quantum phases are key to understanding novel electronic behaviors.
• Fractional quantum anomalous Hall (FQAH) states are exotic topological phases.
• The theoretically predicted ν=-1/3 FQAH state has been elusive, with its nature debated.

Purpose of the Study:

• To optically detect and characterize the elusive ν=-1/3 FQAH state.
• To investigate the role of twisted MoTe2 bilayers in hosting FQAH states.
• To differentiate between charge density wave and topological Chern insulator interpretations.

Main Methods:

• Optical detection using photoluminescence (PL) and reflective magnetic circular dichroism (RMCD).
• Systematic tuning of FQAH states via a vertical electric field.
• Theoretical validation using exact diagonalization calculations.

Main Results:

• Observation of ferromagnetic states at filling factors ν=-1, -2/3, and -1/3 in twisted MoTe2 bilayers.
• The ν=-1/3 FQAH state exhibits lower Curie temperatures and electric field stability, suggesting fragility.
• PL spectra at ν=-1/3 show dispersion with magnetic field, indicative of a nontrivial topological origin.

Conclusions:

• The study provides the first optical detection of the ν=-1/3 FQAH state in twisted MoTe2 bilayers.
• The findings support the interpretation of this state as a topologically nontrivial Chern insulator.
• This work opens new avenues for exploring strongly correlated quantum phases in moire systems.