New spin-polarized electron source based on alkali-antimonide photocathode

TL;DR

This paper predicts and demonstrates a new alkali-antimonide photocathode capable of producing highly spin-polarized electron beams with low emittance, suitable for accelerator applications.

Contribution

It introduces a novel spin-polarized electron source based on alkali-antimonide heterostructures, combining theoretical predictions with experimental validation.

Findings

High degree of electron spin polarization achieved.

Electron beams with emittance near thermal limits.

Proposed vacuum tablet-type sources for accelerators.

Abstract

New spin-dependent photoemission properties of alkali antimonide semiconductor cathodes are predicted based on the detected optical spin orientation effect and DFT band structure calculations. Using these results, the Na$_2$KSb/Cs$_3$Sb heterostructure is designed as a spin-polarized electron source in combination with the Al$_{0.11}$Ga$_{0.89}$As target as a spin-detector with spatial resolution. In the Na$_2$KSb/Cs$_3$Sb photocathode, spin-dependent photoemission properties were established through detection of high degree of photoluminescence polarization and high polarization of the photoemitted electrons. It was found that the multi-alkali photocathode can provide electron beams with emittance very close to the limits imposed by the electron thermal energy. The vacuum tablet-type sources of spin-polarized electrons have been proposed for accelerators, that can exclude the construction of the photocathode growth chambers for photoinjectors.