New Spin-Polarized Electron Source Based on Alkali Antimonide Photocathode.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Optics

Background:

• Alkali antimonide semiconductors are crucial for photocathodes.
• Understanding spin-dependent photoemission is vital for advanced electron sources.
• Optical spin orientation and DFT calculations are key theoretical tools.

Purpose of the Study:

• To predict novel spin-dependent photoemission properties of alkali antimonide semiconductor cathodes.
• To design a heterostructure photocathode and a spin detector for spin-polarized electron generation.
• To explore the potential of these systems for high-quality electron beams in accelerators.

Main Methods:

• Density Functional Theory (DFT) band structure calculations.
• Detection of optical spin orientation effect.
• Fabrication and characterization of Na_{2}KSb/Cs_{3}Sb heterostructure photocathodes.
• Use of Al_{0.11}Ga_{0.89}As as a spin detector.

Main Results:

• Predicted spin-dependent photoemission properties of alkali antimonide cathodes.
• Demonstrated high photoluminescence polarization and photoemitted electron polarization in Na_{2}KSb/Cs_{3}Sb photocathodes.
• Achieved electron beams with emittance near the thermal limit.
• Proposed vacuum tablet-type sources for spin-polarized electrons.

Conclusions:

• Alkali antimonide photocathodes exhibit significant spin-dependent photoemission properties.
• The designed heterostructure serves as an efficient spin-polarized electron source.
• The findings pave the way for advanced spin-polarized electron sources in accelerators, simplifying injector design.