The NMR Probe of High-T c Materials

Transcription

1 R.E. Walstedt The NMR Probe of High-T c Materials 4y Springer

2 Contents Introduction The Basic Phenomenology of High-T c. Materials Carrier Doping and the Master Phase Diagram The NMR Probe Outline of the Remaining Chapters Summary of Chapter 2 - NMR Review Summary of Chapter 3 - Preliminary Cuprate NMR Summary of Chapter 4 - The Pseudogap Summary of Chapter 5 - T\ Models Summary of Chapter 6 The Dynamical Susceptibility. 9 References 10 Introduction to NMR Studies of Metals, Metallic Compounds, and Superconductors Basic NMR Phenomenology The Basic Hamiltonian for NMR Spectra Observation of NMR/NQR Signals Definition and Interpretation of NMR parameters: 7->.. 1!) Definition and Interpretation of NMR parameters: The shift tensor K fll -j Definition and Interpretation of NMR parameters: 7'i NMR Probe of sp-band Metals and Typo I Superconductors NMR Shifts and Relaxation in Simple Pauli Paramagnets The Moriva Theory of Exchange Enhancement in Simple Metals 3(> NMR in the Superconducting State of Simple Metals.. 3N 2.3 Static and Dynamic Magnetism in d-band Metals The d-electron HF Interactions I.", Orbital Shift and Susceptibility l(i Spin-Lattice Relaxation Effects for d-band Electrons... 51) NMR Studies of 3d Metals as Type-II Superconductors. 53

3 X Contents Tj Phenomenology for Type-II Superconductors 58 References 63 3 The Superconducting Cuprates: Preliminary Steps in their Investigation via NMR Cuprate Structures and Doping Effects: LSCO and YBCO LSCO: A superconductor with T c (max) ~ 40K The 92 K Superconductor YBa 2 Cu 3 O 7 _. T (YBCO) Physical Models of Itinerant Quasiparticles in Cuprates Early NMR/NQR Studies: The Early Predominance of YBCO NMR Shift and Relaxation of the 89 Y in YBCO Establishing the Site Assignment for the Cu(l) and Cu(2) NQR Spectra Variation of the 89 Y shift K 89 (x) with x for YBCO6+X Physical Models for the Relaxation of 63 Cu(2) in YBCO Introduction of the Spin Hamiltonian Model for the Cu Experimental Breakthrough: Oriented Powder Samples The Mila-Rice-Shastry Model: A Universal HF Tensor for the Cuprates General Definition of the HF Tensors Extracting the Cu(l,2) HF tensors for YBCO7 from Shift and Susceptibility Data Using the Spin Hamiltonian Model Quantum Chemistry of YBCO7 and the Hyperfine Tensor Ti Ratios and Electron Spin Correlation Effects Incorporating 17 O and 89 Y data into the Mila-Rice-Shastry Picture Measurements of T] for 17 O in YBCO The One-Band, Two-Band Debate: 89 Y and 17 O(2,3) NMR in YBCO Formulation of Ti in Terms of x"(q,uj) and g-dependent HF Couplings Derivation of Dynamical Susceptibility Ti Equation The Fluctuation-Dissipation Theorem A d-wave Model for the NMR Shift and Ti at T < T c The NMR Shift Behavior for T < T c The Monien-Pines Calculations of NMR Shifts below T c Calculating the Relaxation Decay Curve 108 References 112

4 Contents XI Pseudogap Effects in Cuprate NMR Studies The Pseudogap in Oxygen-Deficient YBCO7-X HF Parameters for YBCO6.63 from Scaling of Shift Data A Simple Model Theory of Spin Dynamics for YBCO INS Data for the Pseudogap of Underdoped YBCO A Comprehensive Tj Data Set for YBCO Pseudogap Phenomenology with Other Probes Pseudogap Effects in the Electronic Specific Heat ARPES Studies of Pseudogapped Cuprates Pseudogap Behavior of YBa 2 Cu (Y248) NMR Shift and Relaxation Behavior in Y Measuring the Pseudogap Isotope Effect in Y248 with NMR Theory of the Pseudogap by Varma Effect of Zn impurities on the Pseudogap in Y "Pseudogap-like" Effects in La 2 _. x Sr. r CuO 4 (LSCO:x) Spin Susceptibility Scaling for La 2 _ x Sr. r CuO Behavior of the 17 O and 63 Cu NMR Shifts in LSCO:x Cu NQR spectra and Contrasting T x Behaviors in LSCO:x 153 References 156 Relaxation Models for Cuprate NMR The Uldry-Meier Parameterization Model Basic Formulation of the UM Analysis The Uldry-Meier Analysis of YBCO The Uldry-Meier Analysis of YBCO The Uldry-Meier Analysis of YBa^CiuO* (Y248) The Millis. Monien. and Pines Model for Ti in Cuprates Ti Model for YBCO Using INS Data for \"(q. ^) The Gaussian Model Susceptibility Comparison with the UM Analysis Results for YBCO A Small-U Hubbard Model of Cuprate Spin Dynamics Basic Formulation of the Dynamic Susceptibility 1N Remarks on the Hubbard Model Calculations 18!) 5.5 The Large-U Hubbard Model of Si. Levin et al Relaxation via Orbital Currents proposed by Varma Relaxation of Planar 63 Cu and 17 O at T < T r \"{q.m) for the Small-U Hubbard Model at T < T,.... 2( T; and Spin-Spin Correlations below T, : The I'M Analysis 207 References 210

5 XII Contents 6 Dynamic Susceptibility Studies for the Cuprates The Indirect Spin-Spin Coupling Theory of Pennington and Slichter Some General Properties of the Indirect Spin-Spin Coupling The Gaussian model of Indirect Spin-Spin Coupling in YBCO Measuring Indirect Spin-Spin Coupling via Spin-Echo Decay Behavior and Interpretation of Indirect Couplings in YBCO and Y The Bulut-Scalapino Calculation of 1/T 2g for T < T c Coordinated Interpretation of NMR and INS Data for LSCO Review of INS Data for Optimally-Doped LSCO Interpretation of 63 Cu and 17 O T 2 Data with INS Data for x'(q) The Sokol-Barzykin-Pines Scaling Theory of x(q, w) Phase Diagram and Basic Relationships for Ti, T 2g The Dynamical Crossover Study by Curro et al: Y References 250 A Appendices 253 A.I Some Basic Properties of Spin Echoes 253 A.1.1 Basic Derivation of the Two-Pulse Spin Echo 253 A.1.2 Modelling Spin-Echo Decay 257 A.2 The Gaussian Decay Time T% g for Indirect Spin-Spin Coupling 257 A.2.1 Indirect Coupling with a Gaussian Susceptibility 258 A.3 Spin Echo Decay via Spin-Lattice Relaxation 260 References 261 Index 263