Atomic-Scale Spin-Valve Control of Interlayer Excitons in Twisted WSe₂/CrSe₂/WSe₂ Heterostructures

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Optics

Background:

• Transition-metal dichalcogenide (TMD) van der Waals heterostructures host interlayer excitons with unique properties like long lifetimes and valley-selective optical rules.
• Efficient and active control over the formation and recombination of these interlayer excitons remains a significant challenge in the field.

Purpose of the Study:

• To demonstrate an interface-engineering strategy for achieving magnetic control of interlayer excitons.
• To explore the use of a monolayer ferromagnet as a spin-valve spacer for manipulating excitonic states.

Main Methods:

• Fabrication of a twisted WSe2 homobilayer with an inserted monolayer CrSe2 ferromagnet.
• Low-temperature photoluminescence spectroscopy to probe exciton dynamics and charge transfer.
• Application of external magnetic fields and analysis of thermomagnetic signatures near the Curie temperature.
• First-principles calculations to support experimental findings and investigate spin filtering mechanisms.

Main Results:

• The CrSe2 insertion effectively suppresses interlayer coupling and exhibits thermomagnetic signatures near its Curie temperature (∼65 K).
• External magnetic fields (up to 9 T) reversibly modulate interlayer-exciton emission while enhancing intralayer emission, indicating spin-selective tunneling.
• First-principles calculations confirm CrSe2-mediated spin filtering and reveal dependence on stacking angle.

Conclusions:

• Magnetic spin filtering via interface engineering is an effective strategy for controlling interlayer excitons in TMD heterostructures.
• This approach opens new avenues for developing spin-exciton hybrid architectures and atomic-scale quantum optoelectronic devices.