Long lifetime polarized electron beam production from negative electron affinity GaAs activated with Sb-Cs-O: Trade-offs between efficiency, spin polarization, and lifetime

Cultrera, L.; Galdi, Alice; Bae, Jai Kwan; Ikponmwen, Frank; Maxson, Jared; Bazarov, Ivan

doi:10.1103/physrevaccelbeams.23.023401

Cited by 19 publications

(7 citation statements)

References 34 publications

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“…A possible experimental realization of the suggested spin filter is to dope the outer layer of a GaAs superlattice with two layers of magnetic adatoms. This should be possible without considerable fine tuning, because current state-of-the-art polarizers for microscopy applications are already based on negative electron affinity GaAs superlattice photocathodes [55][56][57][58] . The observed spin polarization in those setups can be larger than 80% and the corresponding quantum efficiency is on the order of several percent.…”

Section: Discussionmentioning

confidence: 99%

Filtering spins by scattering from a lattice of point magnets

2020

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Nature creates electrons with two values of the spin projection quantum number. In certain applications, it is important to filter electrons with one spin projection from the rest. Such filtering is not trivial, since spin-dependent interactions are often weak, and cannot lead to any substantial effect. Here we propose an efficient spin filter based upon scattering from a two-dimensional crystal, which is made of aligned point magnets. The polarization of the outgoing electron flux is controlled by the crystal, and reaches maximum at specific values of the parameters. In our scheme, polarization increase is accompanied by higher reflectivity of the crystal. High transmission is feasible in scattering from a quantum cavity made of two crystals. Our findings can be used for studies of low-energy spin-dependent scattering from two-dimensional ordered structures made of magnetic atoms or aligned chiral molecules.

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Section: Discussionmentioning

confidence: 99%

Filtering spins by scattering from a lattice of point magnets

2020

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“…When grown thin enough, this activating layer preserves the high electron spin polarization of superlattice GaAs [14]. Critically, while both Cs 3 Sb and Cs 2 Te must also be operated in pure vacuum, they are far more robust than the previous monolayer Cs-based coatings; in low-voltage test chambers, these spin-preserving activating layers have been shown to have significantly longer lifetimes [15].…”

Section: Rf High-brightness Polarized Photo-injectormentioning

confidence: 99%

C$^3$ Demonstration Research and Development Plan

Nanni¹,

Breidenbach²,

Vernieri³

et al. 2022

Preprint

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“…However, these photocathodes are very sensitive to any vacuum instability, and their preparation is complex. Although gallium arsenide (GaAs) photocathodes have many disadvantages, such as being difficult to prepare, a low robustness and a short lifetime of only several hundred hours, they are the only photocathodes providing spin-polarized electrons [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Influence of Surface Cleaning on Quantum Efficiency, Lifetime and Surface Morphology of p-GaN:Cs Photocathodes

et al. 2022

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Accelerator scientists have high demands on photocathodes possessing high quantum efficiency (QE) and long operational lifetime. p-GaN, as a new photocathode type, has recently gained more and more interest because of its ability to form a negative electron affinity (NEA) surface. Being activated with a thin layer of cesium, p-GaN:Cs photocathodes promise higher QE and better stability than the known photocathodes. In our study, p-GaN samples grown on sapphire or silicon were wet chemically cleaned and transferred into an ultra-high vacuum (UHV) chamber, where they underwent a subsequent thermal cleaning. The cleaned p-GaN samples were activated with cesium to obtain p-GaN:Cs photocathodes, and their performance was monitored with respect to their quality, especially their QE and storage lifetime. The surface topography and morphology were examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM) in combination with energy dispersive X-ray (EDX) spectroscopy. We have shown that p-GaN could be efficiently reactivated with cesium several times. This paper systematically compares the influence of wet chemical cleaning as well as thermal cleaning at various temperatures on the QE, storage lifetime and surface morphology of p-GaN. As expected, the cleaning strongly influences the cathodes’ quality. We show that high QE and long storage lifetime are achievable at lower cleaning temperatures in our UHV chamber.

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Long lifetime polarized electron beam production from negative electron affinity GaAs activated with Sb-Cs-O: Trade-offs between efficiency, spin polarization, and lifetime

Cited by 19 publications

References 34 publications

Filtering spins by scattering from a lattice of point magnets

Filtering spins by scattering from a lattice of point magnets

C$^3$ Demonstration Research and Development Plan

Influence of Surface Cleaning on Quantum Efficiency, Lifetime and Surface Morphology of p-GaN:Cs Photocathodes

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