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SOLID STATE PHYSICS

SOLID STATE PHYSICS. C. Vettier Institut Laue Langevin. SOLID STATE PHYSICS. SOLID STATE PHYSICS. Understanding of bulk properties Ground states Susceptibilities Simplifying but consistent patterns Characterisation of phase diagrams Structures Relevant external fields

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SOLID STATE PHYSICS

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  1. SOLID STATE PHYSICS C. Vettier Institut Laue Langevin

  2. SOLID STATE PHYSICS

  3. SOLID STATE PHYSICS • Understanding of bulk properties • Ground states • Susceptibilities • Simplifying but consistent patterns • Characterisation of phase diagrams • Structures • Relevant external fields • Measure of fluctuations • Time and Space • Dynamical susceptibilty

  4. FRONTIERS IN SOLID STATE PHYSICS Physics moves towards complexity coupled degrees of freedom low dimensionality Electron charge, spin, orbit, Lattice Soliton modes in CuGeO3 H. Ronnow et al., 2002

  5. FRONTIERS IN SOLID STATE PHYSICS Biggest unsolved problems ? plenty ! Self-organised complexity Inhomogeneity Exotic superconductivity

  6. FRONTIERS IN PHYSICS OF SOLIDS Superconductivity Discovery in 1911 – in Leiden Successful model in 1957 - BCS Before mid-80’s Tc restricted to below 23 K 1986 Discovery of High Tc systems Cuprates materials Bednorz & Müller 36 K, 90K and 130 K

  7. FRONTIERS IN PHYSICS OF SOLIDS Superconductivity Challenge : Nature of couplings remains puzzling despite an extraordinary activity Applications magnetic resonance imaging power transport

  8. attraction through lattice modes BCS k m SUPERCONDUCTIVITY model : glue-ing of electrons

  9. Phonon wave s-wave pairs electron electron Magnetic Exciton wave d-wave pairs P. Coleman, 2001 exotic couplings magnetism SUPERCONDUCTIVITY No consensus on a global model despite tremendous efforts

  10. SUPERCONDUCTIVITY Neutrons : unique and necessary tool Use all possible methods Structures and motions of particles Separation of lattice and magnetic effects

  11. Tc Resistivity 0 20 40 60 80 100 Temperature (K) B Mg Tc B Susceptibility 0 10 20 30 40 50 60 Temperature (K) BCS superconductivity MgB2 Tc ~ 39 K J. Nagamatsu et al., 2001

  12. Phonon density of states B layer -orbitals Mg 0 20 40 60 80 100 Energy (meV) R. Osborn et al., 2001 -orbitals B - bond stretching modes BCS superconductivity MgB2 Inelastic neutron scattering

  13. Mg1-xAlxB2 Susceptibility Temperature (K) J.S. Slusky et al., 2001 BCS superconductivity Aluminium doping destroys superconductivity ZMg = 12 At. WeightMg = 24.3 ZAL = 13 At. WeightAl = 27.0 Electron doping

  14. Phonon density of states 20 15 10 5 0 0 25 50 75 100 125 150 ENERGY (meV) BCS superconductivity Renormalisation of phonon modes MgB2 AlB2 Neutrons identify key phonon modes B. Renker et al., 2002

  15. BCS superconductivity

  16. BCS superconductivity Vortex lattices penetration depth anisotropy Small angle neutron scattering

  17. Ch. Dewhurst, B. Cubitt, 2002 BCS superconductivity SANS from Vortex Lattices in MgB2 Isotropic penetration depth

  18. BCS superconductivity Neutrons have unravelled the binding mechanism in MgB2 More neutrons are needed to discover couplings in exotic superconductors

  19. Exotic superconductivity • Fluctuations • coupling of quasi - particles • Dynamics is essential • Neutron scattering • effects of lattice, • electron spins and charges • Neutron polarisation

  20. Superconducting YBa2Cu3O7 Non-superconducting YBa2Cu3O6 Charge reservoir Exotic superconductivity Cuprate oxides Neutron diffraction

  21. anomalous metal temperature metal doping FLUCTUATIONS IN SOLIDS : THE GLOBAL VIEW HTc superconductors cuprate oxides Phase diagram

  22. QAF FLUCTUATIONS IN SOLIDS : THE GLOBAL VIEW Antiferromagnetic phase Normal excitations : spin waves

  23. QAF QAF Doping FLUCTUATIONS IN SOLIDS : THE GLOBAL VIEW Antiferromagnetic phase Superconducting phase

  24. X=0.5 YBa2Cu3O6+x X=0.52 X=0.83 X=0.92 T = 2 K X=1.00 Imaginary part of susceptibility () 0 10 20 30 40 Energy (meV) FLUCTUATIONS IN SOLIDS : THE GLOBAL VIEW Magnetic response at QAF slice in Q space

  25. QAF Intensity Energy (meV) YBCO6.85 J. Rossat-Mignod et al., 1991 FLUCTUATIONS IN SOLIDS : THE GLOBAL VIEW Observation of resonance peak

  26. QAF YBCO6.6 P. Dai et al., 1999 FLUCTUATIONS IN SOLIDS : THE GLOBAL VIEW Extraction of magnetic response Broad dynamical range Where is the interesting range in Q and energy?

  27. resonance Energy (meV) QAF Q = Q - QAF in reciprocal lattice units YBCO6.85 L.P. Regnault et al., 2002 FLUCTUATIONS IN SOLIDS : THE GLOBAL VIEW Close look at resonance Polarisation analysis Unusual dispersion

  28. FLUCTUATIONS IN SOLIDS : THE GLOBAL VIEW Obtaining more data is required Broad range in frequency from 1 neV to 100 meV and Q space Coupling to all degrees of freedom polarisation analysis

  29. Phonon energy (meV) Q in reciprocal lattice units Egami et al., (2002) FLUCTUATIONS IN SOLIDS : THE GLOBAL VIEW Neutrons will be needed to unravel the relevant couplings Phonon dispersion in YBa2 Cu3 O 7-x

  30. FLUCTUATIONS IN SOLIDS : THE GLOBAL VIEW Many examples in other fields Quantum spin chains M. Enderle et al., 2001 Mapping a wide time and space domain

  31. FLUCTUATIONS IN SOLIDS : THE GLOBAL VIEW • ESS offers unprecedented capabilities : • flux • coverage of (t,r) space • neutron polarisation analysis • ESS will allow to reach new scientific • frontiers

  32. Mg B Mg11B2 Mg10B2 Magnetisation Temperature (K) S.L. Bud’ko et al., 2001 BCS superconductivity MgB2 Tc ~ 39 K Isotopic effects Marginal shift with Mg isotope change

  33. Conventional BCS No node in the gap (Intensity)1/2 Temperature (K) Ch. Dewhurst ,B. Cubitt, 2002 BCS superconductivity Vortex Lattice in MgB2 Isotropic penetration depth

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