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Spin filters as high-performance spin polarimeters

PESP-2002 Workshop, Middleton. Spin filters as high-performance spin polarimeters. N. Rougemaille , H.-J. Drouhin, A. Filipe, G. Lampel, Y. Lassailly, J. Peretti, A. Schuhl, T. Wirth. Spin polarimeters still under investigation. Usual spin detector features :

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Spin filters as high-performance spin polarimeters

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  1. PESP-2002 Workshop, Middleton Spin filters as high-performance spin polarimeters N. Rougemaille, H.-J. Drouhin, A. Filipe, G. Lampel, Y. Lassailly, J. Peretti, A. Schuhl, T. Wirth

  2. Spin polarimeters still under investigation • Usual spin detector features: low-collection efficiency, poor sensitivity to the spin polarization, inconvenient practical use • Optimized efficiency: Mott polarimetry Ghiringhelli et al. Rev. Sci. Inst. 70, 4225 (1999). Qiao et al. Rev. Sci. Inst. 68, 4390 (1997). Absorption / reflection detector Bertacco et al. APL 72, 2050 (1998). Bertacco et al. Rev. Sci. Inst. 70, 3572 (1999). Spin filter Cacho et al. PRL 88, 066601 (2001). • What is the situation for spin filtering now ?

  3. Spin filter concept Spin filter features : Spin sensitivity can be close to one. But the transmission decays exponentially.  limits the practical use for spin detection .

  4. Previous works Drouhin et al. J. Appl. Phys. 79, 4734 (1996). • Overlayer technique, direct transmission • Free-standing Au/Co foil Transmission 10-4 Ep=2.9 eV Cesiated exit face

  5. Starting point • Solid-state device

  6. Filipe et al. Phys. Rev. Lett. 80, 2425 (1998).

  7. Experimental setup • Electron production • Electron transportation • Signal detection Energy increased up to 1 keV

  8. Current measurements

  9. Energy Distribution Curves

  10. Around zero

  11. Summary

  12. Operating features of the detector • Spin-dependent absorption of electrons in a ferromagnetic metal • Compact • Convenient • Performant Siegmann et al. ,Phys. Rev. Lett. 46, 452 (1981).

  13. Remaining questions • What is the origin of the magnetic signal increase with increasing energy ? • Decrease of the polarization dilution in Pd ? • Increase of the IMFP in Pd ? • Exchange integral ? • Increase of the energy distribution width at the Schottky interface ? • Increase of the spin-filtering efficiency in Fe ? (not enough)

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