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“Big Facility” Physics in Grenoble. Sub Heading. ESRF: X-rays. ILL: neutrons. “Big Facility” Physics near Zurich - Paul Scherrer Institut. S m S: muons. SINQ: neutrons. SLS: X-rays. Low energy muons for investigation of:. Magnetic fields in thin films and surfaces.

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  1. “Big Facility” Physics in Grenoble Sub Heading ESRF: X-rays ILL: neutrons Big Facility Physics 26th Jan 2004

  2. “Big Facility” Physics near Zurich - Paul Scherrer Institut SmS: muons SINQ: neutrons SLS: X-rays Big Facility Physics 26th Jan 2004

  3. Low energy muons for investigation of: Magnetic fields in thin films and surfaces Big Facility Physics 26th Jan 2004

  4. The apparatus for producing a beam of low energy muons Big Facility Physics 26th Jan 2004

  5. the muons come in <= HERE with 4 MeV energy and are spin- polarised Original apparatus designed and constructed by E. Morenzoni at Paul Scherrer Institut muons are implanted in the sample surface <= HERE at a tuneable energy of 1 - 30 keV Big Facility Physics 26th Jan 2004

  6. WHY USE (+ve) MUONS ? • the spin-polarised • muon arrives • in the sample • its spin precesses • in the local B-field • it decays, giving an e+ in about 2 ms • the e+ tends to be emitted along the muon spin direction Big Facility Physics 26th Jan 2004

  7. The muon spin sweeps around like a lighthouse - the probability of an e+ arriving at a fixed detector => oscillates (and decays) with time (after implantation) After implanting a large number of muons... => Big Facility Physics 26th Jan 2004

  8. The frequency of precession measures the magnetic field AT the muon ... ... which has been implanted at a known depth - - controlled by its energy... Big Facility Physics 26th Jan 2004

  9. T.J. Jackson et al. Phys. Rev. Lett. 84, 4958-4961 (2000) increasing temperature Field Distance below surface of YBCO First ever measurement of field profile on a nm scale justinside a superconductor Big Facility Physics 26th Jan 2004

  10. Current Developments • new samples: • low Tc super-conducting films • ferromagnetic-normal and ferro-superconducting multilayers • CMR+HighTc films • micro-structured superconductors a new muon moderation cryostat - developed in Birmingham -and a new x 10 intensity muon beamline being developed at PSI Big Facility Physics 26th Jan 2004

  11. Current Flux lines Motion Type-II superconductor Current Magnetic Flux Lines in superconductors Each flux line Carries a flux of F0 = h/2e Big Facility Physics 26th Jan 2004

  12. H Hc2 H normal state D=3 Plastic Vortex Glass Smectic vortex liquid vortex solid Fc Bragg glass F Moving Bragg glass Meissner state T Tc Liquid T Vortex Matter Dynamical Phase Diagram Vortex Matter H -T Phase Diagram Big Facility Physics 26th Jan 2004

  13. Detected by small-angle neutron diffraction SANS Big Facility Physics 26th Jan 2004

  14. EPSRC – funded 11 T cryomagnet Diffraction pattern from a D Flux Lattice in niobium Big Facility Physics 26th Jan 2004

  15. Results from YBCO => Phys Rev Lett, Feb 2004 Four stretched triangular lattices at low fields B = 1 T pattern Big Facility Physics 26th Jan 2004

  16. Results from YBCO => Phys Rev Lett, Feb 2004 Due to fourfold symmetry of d-wave flux line cores Square lattice of flux lines at high fields B = 11 T pattern Big Facility Physics 26th Jan 2004

  17. Calculations of flux lattice structure and energy lowest energy s-wave: but forced to be square d-wave observed orientation d-wave: orientation rotated 45 deg Big Facility Physics 26th Jan 2004

  18. Future Work – mainly on “Vortex Matter” • flux lattice structures and pairing mechanisms in • unconventional superconductors • flux lattice melting in low-Tc superconductors • X-ray observation of flux line cores • flux line motion and motion-induced ordering • flux-line-like molecular structures • Other neutron scattering, including inelastic neutron • scattering studies of fluctuations near QCP in Sr3Ru2O7 Big Facility Physics 26th Jan 2004

  19. Future Developments in neutron scattering Spallation Neutron Source, Oak Ridge USA Big Facility Physics 26th Jan 2004

  20. European Spallation Source? Probably in the UK ILL will be competitive for the next 10 years Big Facility Physics 26th Jan 2004

  21. Big Facility Physics 26th Jan 2004

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