Publications
Publication Information
| Title | Half-Metal Spin Filter for Highly Polarized Emission from GaAs Photocathodes |
| Authors | Shashi Poddar, C.-J. Jing, E. Montgomery, P. Lukashev, C. Palmstrøm, Marcy Stutzman, Shukui Zhang |
| JLAB number | JLAB-ACC-21-3500 |
| LANL number | (None) |
| Other number | DOE/OR/23177-5352 |
| Document Type(s) | (Meeting) |
| Category: | Diagnostics & Instrumentation |
| Associated with EIC: | No |
| Supported by Jefferson Lab LDRD Funding: | No |
| Funding Source: | Nuclear Physics (NP) |
| Other Funding: | DE-SC0020564 |
|
Meeting Paper compiled for IPAC21 Proceedings Proceedings of IPAC 2021 Edited By Liu Lin, John M. Byrd, Regis Neuenschwander, Renan Picoreti, Volker R. W. Schaa JACOW (2021) Page(s) 2833-2836 | |
| Publication Abstract: | GaAs-based photocathodes are one of the major sources of spin-polarized electrons and are crucial for the upcoming Electron-Ion collider experiments which includes study of proton spin and spin parity violation in the standard model. The theoretical polarization limit in unstrained GaAs photocathodes is 50 % but only 35 % is routinely achieved in experiments. Spin selective filtering allows to boost the spin polarization beyond the 50 % theoretical limit. In this work, first-principle electronic calculations using standard Density Functional Theory are performed to predict possible Heusler alloy half-metal candidates to be used as spin-filter. Simulations are also performed to investigate the half-metallicity as function of the magnetic spin direction. Several devices are experimentally fabricated using dedicated Molecular Beam Epitaxy growth system. We implemented Quantum Efficiency and Polarization testing of these half-metal/GaAs heterostructures using a dedicated Mott polarimeter system. Photoemission can also be seen on magnetically switching the spin-filter direction accompanied by a change in sign of the asymmetry which is a qualitative proof of the spin-filtering effect. |
| Experiment Numbers: | |
| Group: | Ctr for Injectors&Sources |
| Document: | |
| DOI: | https://doi.org/10.18429/JACoW-IPAC2021-WEPAB102 |
| Accepted Manuscript: | wepab102.pdf |
| Supporting Documents: | |
| Supporting Datasets: | |