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Neutron Scattering on

Neutron Scattering on. High Transition Temperature Superconductors Miaoyin Wang Solid State Physics II: Presentation II Apr., 2010 @ UTK. Outline. 1. High T c Superconductor 2. Neutron Scattering 3. Neutron Scattering on High T c Superconductor. 1. Superconductor.

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Neutron Scattering on

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  1. Neutron Scattering on High Transition Temperature Superconductors Miaoyin Wang Solid State Physics II: Presentation II Apr., 2010 @ UTK

  2. Outline 1. High Tc Superconductor2. Neutron Scattering3. Neutron Scattering on High Tc Superconductor

  3. 1. Superconductor *Resistance = 0 at Tc*Meissner Effect Tc Songxue Chi et al., PRL Transition Temperature

  4. 1. Superconductor *More Magnetic Field … H SC II SC Temperature Tc

  5. 1. Superconductor BCS Theory = Bardeen & Cooper & Schrieffer Phonon ="glue"

  6. 2. High-Tc Superconductor More system to compare Cu is not so special! From Wikipedia

  7. 2. High-Tc Superconductor Property:Structure Shiliang Li et al., Wuli S. Chi et al., PRL Shiliang Li et al., PRB

  8. 2. High-Tc Superconductor Property: Doping & Phase Diagram

  9. 3. Neutron Scattering Neutron: No Charge >Go deep into sample – a bulk detector Spin 1/2 >Nuclear / Magnetic Structure 1 GeV For Neutron Energy ~ 1meVWavelength ~ 0.1-1 nm

  10. 3. Neutron Scattering Neutron Cross-Section Neutron Loves H! Be aware of plastic... From NCNR Website

  11. 3. Neutron Scattering Neutron ScatteringWhat we are interested in?1. Elastic & Inelastic2. Energy & Momentum (transfer)3. Intensity ?

  12. 4. Experiment No.1 Structure and magnetic phase diagram of CeFeAsO1-xFx and its relation to high-temperature superconductivityJun Zhao et al., Nature Materials 7 , 953-959 (2008). About Experiment1. Powder Sample CeFeAsO1-xFx2. Elastic3. Nuclear / Magnetic Bragg peak

  13. 4. Experiment No.1 About Instrument: Powder Diffractometry HB-2A in HFIR, ORNL

  14. 4. Experiment No.1 What the data look like…

  15. 4. Experiment No.1 What we have found… Structure distortion1. Suppressed like AFM order by doping.2. Totally disappear in SC phase.

  16. 4. Experiment No.1 What we have found…

  17. 4. Experiment No.2 Resonance in the electron-doped high-transition-temperature superconductor Pr0.88LaCe0.12CuO4-δWilson S D et al., Nature, 2006, 442:59 About Experiment1. Single Crystal Sample Pr0.88LaCe0.12CuO4-δ2. Inelastic3. Spin resonance

  18. 4. Experiment No.2 ki About Instrument: Triple-axis Spectrometry Q kf BT-2 in NCNR, NIST

  19. 4. Experiment No.2 Spin Resonance

  20. 4. Experiment No.2 Data

  21. 4. Experiment No.2 Result

  22. Summary 1.Structure distortion is strongly related to AFM order and superconductivity.2. Structure distortion is suppressed with doping, and vanishes in the SC phase.3. Spin Resonance independence with doping type (hole or electron).4. Resonance energy is always proportional to Tc, which suggests that the resonance is the universal feature in high-Tc superconductor.

  23. Thank you!

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  26. Thank you!

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