Large enhancement of spin polarization observed by photoelectrons from a strained GaAs layer
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Cited by (131)
An overview of how parity-violating electron scattering experiments are performed at CEBAF
2023, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentMeasurement of electron beam polarization from unstrained GaAs via two-photon photoemission
2014, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentCitation Excerpt :The first GaAs-based polarized electron source used at an accelerator [2] provided beam polarization ~35%, with a theoretical maximum polarization limited to 50% [3,4] due to the heavy-hole, light-hole energy level degeneracy of the 2p3/2 valence band state (Fig. 1a). Significantly higher beam polarization was obtained in the 1990s by introducing an axial strain within the GaAs crystal structure [5–7] which eliminates this degeneracy (Fig. 1b). Today, beam polarization at accelerators routinely exceeds 80% using strained-superlattice GaAs/GaAsP structures [8,9]; however, these high-polarization photocathodes are thin compared to typical unstrained bulk GaAs and with respect to the photon absorption depth.
Picosecond electron bunches from GaAs/GaAsP strained superlattice photocathode
2013, UltramicroscopyCitation Excerpt :Therefore, high spin polarization is achieved by breaking the degeneracy between the heavy-hole and light-hole valence bands at the Γ point and by exciting electrons only from one of the bands. The degeneracy can be broken by the use of a strained GaAs layer [6,7], superlattice structures [8], and strained superlattice structures [9–11]. The mechanism for generating a spin-polarized electron beam from a superlattice or strained-superlattice photocathode is shown in Fig. 1.
Photocathodes
2023, Handbook Of Accelerator Physics And Engineering: Third Edition
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Present address: Physikalisches Institut der Universität Bonn, Bonn, Germany.