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Task 4: Development of thin film based Larmor precession devices

Forschungszentrum Jülich. Task 4: Development of thin film based Larmor precession devices. Sub-task B:

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Task 4: Development of thin film based Larmor precession devices

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  1. Forschungszentrum Jülich Task 4:Development of thin film based Larmor precession devices Sub-task B: Developments of thin films with the rotating magnetization and reduced losses in RF field as fast spin turners for compact instrumentation (3-d polarimeter, spin-echo set up).Partners:Forschungszentrum Jülich, Joint Institute of Nuclear Research, Dubna A. Ioffe, FZ Jülich JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  2. Forschungszentrum Jülich Spin propagation through a thin magnetic sheet with rotating magnetic field z • Because of the sheet thickness selection, the neutron spin makes half a turn • Finally spin is again in the sheet‘s plane •  Spin is reflected w.r.t. the direction of magnetic field vector B B s x y JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  3. Forschungszentrum Jülich z t = t1 t = t2 B t = 0 s t = t3  = 2t „The spin clock“ is running twice as quick as „the field clock“ In-plane rotating magnetic field the spin Larmor clock JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  4. Forschungszentrum Jülich  = 2T t = t1 T t = 0  T t = t2 T t = t3 T Two spin turners Spin turner 2 Spin turner 1 z H = 0 x y L T t = t1 t = 0 t = t2  = 2t t = t3 Position of spin depends only on T and doesn’t depend on the arrival time t ! JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  5. Forschungszentrum Jülich Intensity modulations of the incident beam spectrum After analyzer: We achieve high-frequency modulation of the spectrum. Modulation frequency is defined by the product L. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  6. Neutron spin echo setup Forschungszentrum Jülich Spin turner 2 Spin turner 4 x Spin turner 3 Spin turner 1 z z L L+L y y f = 50 kHz, L2 = L1 = 1 m / = 20% NSE signal: Simulations (VITESS) The modulation frequency ~L (effective „field integral“) The operational principle is rather similar to NRSE JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  7. Forschungszentrum Jülich How to realize the rotating magnetic field? Superposition of two sinusoidal time dependent fields: Spin precession angle:  Spin-flip condition: B(G) ·(Å)·d(cm) = 66 Coil: d = 1 cm,  = 4 Å B = 16.5 G Thin film: d = 25 m,  = 4 Å B = 6600 G JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  8. Forschungszentrum Jülich Thin film spin turner • Thin magnetic foil of metallic glassy alloys (commercially available): • low Hc: 50 –100 mG • high Bc: 6 –8 kG • thickness: d = 25-50 m • high frequency susceptibility (500 kHz and higher) • rather homogenous Suits quite good for  = (2 – 4) Å JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  9. Inelastic scattering Forschungszentrum Jülich • a moderate improvement in the energy resolution of inelastic and quasielastic scattering experiments in a wide angular (Q-) range • E/E = 0.1 % or better (factor 10-20 w.r.t. TOF) • Inexpensive and technically affordable solution E= 15 meV (=2.3 Å, / =1.5% ) (A. Ioffe, S. Manoshin, Physica B: 529(2004) 45) JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  10. Quasielastic scattering Forschungszentrum Jülich (A. Ioffe, S. Manoshin, Physica B: 529(2004) 45) JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  11. The majority of the experimental work is being currently carried out in the cooperation with Joint Institute of Nuclear Research, Dubna,using the pulsed neutron source IBR-2.V. Bodnarchuk will report about details of these experiments. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  12. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  13. z Bg s y x Compensation coil Thin magnetic foil Forschungszentrum Jülich Polarized neutron experiment at IBR-2 - Polarized neutron setup at REFLEX-P Py Sample is placed inside the compensation coil: /2 flipper JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  14. Forschungszentrum Jülich Polarized neutron experiment at IBR-2 Sample: thin filmof metallic glassy alloys Co66Si15B14Fe4Ni (Good Fellow). d = 25 m • Depolarization around B = 0 was not observed. • Control experiment with a shim foil: full depolarization This result has been reconfirmed by vector polarization analysis up at FZJ JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  15. B Forschungszentrum Jülich Vector polarization analysis at FZJ (2004)V. Bodnarchuk (JINR), A. Ioffe (FZJ) Samples: different metal glassy alloys (commercial) Instrument: Set up for 3-d polarization analysis LAP-ND at FZJ • Results: • Spin rotation • Depolarization JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  16. Forschungszentrum Jülich Depolarization on scattered magnetic fields Table of experimental results This alloy is a very good candidate ! Absorption within a few percent JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina * This angle is pure rotation on foil magnetization. It obtained as difference between total turn angle and turn angle of empty coil 23.

  17. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  18. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  19. Forschungszentrum Jülich Quasielastic scattering JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  20. SESANS & SERGIS Forschungszentrum Jülich   Flippers are inclined to achieve higher angular sensitivity  = 4 Å The angular resolution is decoupled from incident beam divergence: the angular resolution is 0.002°, when the incident beam divergence is 0.5°. JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  21. B H Hc Forschungszentrum Jülich Spin turner Thin magnetic foil of a metallic glass alloy: • low Hc: 50 –100 mG (Low current for field control ) • high Bc: 6 –8 kG ! • thickness: d = 25-50 m • high frequency susceptibility (500 kHz and higher) (patterning technique, Si-MG multilayers (Theo)) • No heating – no cooling is required, rather homogenous Spin-flip condition: Satisfied for e.g.  = 4 Å, d = 25m JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina

  22. Forschungszentrum Jülich Co69B12Si12Fe4Mo2Ni A depolarization on scattered magnetic fields? This has been a first and short experiment … However, this MG alloy is already a very good candidate ! JRA5- PNT: Meeting #3, 9-10 June 2005, Gatchina * This angle is pure rotation on foil magnetization. It obtained as difference between total turn angle and turn angle of empty coil 23.

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