Optical control of integer and fractional Chern insulators

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Topological Matter

Background:

• Topological control, especially with electron correlations, is crucial for advanced materials.
• Twisted MoTe2 bilayers are zero-field fractional Chern insulators exhibiting unique quantum Hall effects.
• Ferromagnetic polarization dictates the properties of Chern insulator states.

Purpose of the Study:

• To demonstrate optical control of ferromagnetic polarization in twisted MoTe2 bilayers.
• To investigate the manipulation of Chern insulator (CI) and fractional Chern insulator (FCI) states via optical pumping.
• To explore applications in topological spintronics and quantum information.

Main Methods:

• Circularly polarized optical pumping of twisted MoTe2 bilayers.
• Optical training for on-demand ferromagnetic state preparation.
• Direct optical switching of magnetization below the Curie temperature.
• Spatially resolved measurements to map magnetic domains.

Main Results:

• Achieved on-demand preparation and direct switching of ferromagnetic polarization using helicity-selective optical pumping.
• Demonstrated dynamic control of CI and FCI states by modulating light helicity.
• Observed effective optical control near CI and FCI states due to gap-enhanced valley polarization.
• Successfully performed optical writing of ferromagnetic domains, controlling topological states.

Conclusions:

• Precise optical control of topological quantum many-body systems is achievable in twisted MoTe2.
• This method allows for programmable patterning of topological states, enabling new applications.
• Potential applications include topological spintronics, quantum memories, and the creation of exotic edge states.