Optical valley Hall effect for highly valley-coherent exciton-polaritons in an atomically thin semiconductor

Area of Science:

• Condensed Matter Physics
• Optics
• Materials Science

Background:

• Spin-orbit coupling links charge carrier spin and momentum.
• Synthetic spin-orbit coupling in photonic materials enables spin-based devices.
• Transition metal dichalcogenides offer intrinsic spin-valley properties.

Purpose of the Study:

• To demonstrate spin- and valley-selective propagation of exciton-polaritons.
• To investigate the optical valley Hall effect in monolayer MoSe2.
• To explore potential applications in spin-valley-locked photonic devices.

Main Methods:

• Strongly coupling monolayer MoSe2 to a microcavity photon mode.
• Creating a wire-like device to guide exciton-polaritons.
• Exciting a coherent superposition of K and K' tagged polaritons.

Main Results:

• Observed spin- and valley-selective propagation of exciton-polaritons.
• Demonstrated valley-selective expansion of polaritons without external magnetic fields.
• Achieved a macroscopic optical valley Hall effect.

Conclusions:

• Monolayer MoSe2 in microcavities enables control over exciton-polariton propagation.
• The observed optical valley Hall effect is a promising phenomenon for photonic devices.
• This work paves the way for novel spin-valley-locked photonic technologies.