Bennemann K.H., Ketterson J.B. Superconductivity: Volume 1: Conventional and Unconventional Superconductors; Volume 2: Novel Superconductors
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Contents IX
7 Nanostructured Superconductors
G. Deutscher .................................................................................... 259
7.1 Introduction .................................................................................... 259
7.2 Nano-structuredCompounds ................................................................... 260
7.3 TheGranularStructure.......................................................................... 260
7.4 NormalStateTransport ......................................................................... 262
7.5 SingleGrainBehavior ........................................................................... 265
7.6 WeaklyCoupledGrains:GranularInsulatorsandSuper-Insulators .............................. 269
7.7 WellCoupledGrains............................................................................. 272
7.8 CriticalTemperatureofGranularSuperconductors.............................................. 275
References ............................................................................................. 277
8 Proximity–Coupled Systems: Quasiclassical Theory of Superconductivity
V. Chandrasekhar ............................................................................... 279
8.1 Introduction .................................................................................... 279
8.2 TransportEquationsintheDiffusiveApproximation ............................................ 280
8.3 TheKeldyshGreen’sFunctions.................................................................. 283
8.4 TheQuasiclassicalApproximation............................................................... 288
8.5 Non-equilibriumGreen’sFunctionsforSuperconductingSystems ............................... 291
8.6 QuasiclassicalSuperconductingGreen’sFunctions .............................................. 294
8.7 TheDirtyLimit:TheUsadelEquation ........................................................... 297
8.8 ParametrizationoftheQuasiclassicalGreen’sFunction.......................................... 302
8.9 ApplicationsoftheQuasiclassicalEquationstoProximity-CoupledSystems..................... 304
8.10 Summary........................................................................................ 311
References ............................................................................................. 312
9 Principles of Josephson-Junction-Based Quantum Computation
S. E. Shafranjuk and J. B. Ketterson .............................................................. 315
9.1 Introduction .................................................................................... 316
9.2 Josephson-Junction-BasedQubitDevices........................................................ 319
9.3 QubitDynamics................................................................................. 329
9.4 QuantumOscillationsinTwoCoupledChargeQubits ........................................... 345
9.5 SISISTwo-QubitGatewithIntrinsicCoupling................................................... 350
9.6 Conclusions ..................................................................................... 361
Appendix............................................................................................... 362
References ............................................................................................. 365
10 Fluctuation Phenomena in Superconductors
A. I. Larkin and A. A. Varlamov .................................................................. 369
10.1 Introduction .................................................................................... 370
10.2 Ginzburg–LandauFormalism:Thermodynamics................................................ 373
10.3 FluctuationsBelowtheCriticalTemperature .................................................... 390
10.4 Ginzburg–LandauTheoryofFluctuationsinTransportPhenomena............................. 396
10.5 FluctuationsNeartheS–ITransition ............................................................ 405
10.6 MicroscopicDerivationoftheTime-DependentGinzburg–LandauEquation.................... 410
10.7 MicroscopicTheoryofFluctuationConductivityofLayeredSuperconductors................... 416
10.8 ManifestationofFluctuationsinVariousProperties ............................................. 429
XContents
10.9 Conclusions ..................................................................................... 452
References ............................................................................................. 453
11 Universal Properties of Cuprate Superconductors: Evidence and Implications
T. Schneider ..................................................................................... 459
11.1 Introduction .................................................................................... 459
11.2 CriticalBehavioratFiniteTemperature.......................................................... 465
11.3 QuantumCriticalBehaviorandCrossoverPhenomena.......................................... 471
11.4 ThinFilms ...................................................................................... 487
11.5 ConcludingRemarksandComparisonwithOtherLayeredSuperconductors.................... 487
References ............................................................................................. 489
12 Vortex Matter
G. Blatter and V. B. Geshkenbein ................................................................. 495
12.1 Introduction .................................................................................... 496
12.2 Ginzburg–LandauandLondonTheories ........................................................ 502
12.3 VortexLines..................................................................................... 505
12.4 VortexLattice ................................................................................... 512
12.5 LayeredMaterials ............................................................................... 518
12.6 AnisotropicScalingTheory...................................................................... 532
12.7 StatisticalMechanics ............................................................................ 538
12.8 QuenchedDisorder:PinningandCreep ......................................................... 566
12.9 UncorrelatedDisorder:CollectivePinningandCreep ........................................... 575
12.10 CorrelatedDisorder ............................................................................. 605
12.11 SurfaceandGeometricalBarriers ............................................................... 610
12.12 VortexGlasses................................................................................... 615
12.13 ConcludingRemarks ............................................................................ 621
References ............................................................................................. 625
13 Unconventional Superconductivity in Novel Materials
M. B. Maple, E. D. Bauer, V. S. Zapf, and J. Wosnitza .............................................. 639
13.1 Introduction .................................................................................... 640
13.2 ConventionalSuperconductorsContainingLocalizedMagneticMoments ....................... 641
13.3 f -ElectronHeavyFermionSuperconductors..................................................... 659
13.4 OrganicSuperconductors ....................................................................... 696
13.5 LayeredCuprateandRuthenateSuperconductors ............................................... 717
13.6 ComparisonofthePropertiesofDifferentClassesofNovelSuperconductors.................... 741
References ............................................................................................. 744
Contents XI
Volume II. Superconductivity: Novel Superconductors
ListofContributors .................................................................................... XV
14 High-T
c
Superconductivity
H. R. Ott ........................................................................................ 765
14.1 Introduction .................................................................................... 765
14.2 TypicalStructuralCharacteristics ............................................................... 767
14.3 OccurrenceofSuperconductivity................................................................ 774
14.4 PhysicalPropertiesofCopperOxides............................................................ 778
14.5 Physical Properties of Non-Cuprate High-T
c
Superconductors................................... 813
14.6 FinalRemarks................................................................................... 823
References ............................................................................................. 823
15 Tunneling Spectroscopy of Conventional and Unconventional Superconductors
J. Zasadzinski ................................................................................... 833
15.1 Introduction .................................................................................... 833
15.2 BasicTunnelingPhenomenology................................................................ 835
15.3 TunnelingandStrong-CouplingEffects:MicroscopicPicture .................................... 841
15.4 TunnelingSpectroscopyofConventionalSuperconductors ...................................... 844
15.5 TunnelinginHigh-TemperatureSuperconductors............................................... 847
15.6 HeavyFermionSuperconductors................................................................ 861
15.7 OrganicSuperconductors ....................................................................... 862
15.8 OtherMaterials ................................................................................. 863
15.9 Conclusions ..................................................................................... 864
References ............................................................................................. 865
16 Phase-Sensitive Tests of Pairing Symmetry in Cuprate Superconductors
C. C. Tsuei and J. R. Kirtley ...................................................................... 869
16.1 Introduction .................................................................................... 869
16.2 PhaseSensitiveTests:TheoreticalBackground .................................................. 874
16.3 Phase-SensitiveTests:Experiments.............................................................. 880
16.4 Angle-ResolvedDeterminationofGapAnisotropyinYBCO ..................................... 901
16.5 Universality of the d-WavePairState ............................................................ 902
16.6 Implications of d-WavePairingSymmetry ...................................................... 907
16.7 Conclusions ..................................................................................... 912
References ............................................................................................. 913
17 Photoemission in the High-T
c
Superconductors
J. C. Campuzano , M. R. Norma n, and M. Randeria ............................................... 923
17.1 Introduction .................................................................................... 924
17.2 BasicsofAngle-ResolvedPhotoemission ........................................................ 924
17.3 TheValenceBand ............................................................................... 933
17.4 NormalStateDispersionandtheFermiSurface ................................................. 935
17.5 SuperconductingEnergyGap ................................................................... 948
17.6 Pseudogap ...................................................................................... 954
XII Contents
17.7 PhotoemissionLineshapesandtheElectronSelf-Energy ........................................ 963
17.8 Summary........................................................................................ 987
References ............................................................................................. 988
18 Neutron Scattering and the Magnetic Response of Superconductorsand Related Compounds
S. M. Hayden .................................................................................... 993
18.1 Introduction .................................................................................... 993
18.2 TheNeutronScatteringTechnique .............................................................. 994
18.3 TheStaticSpinSusceptibilityofSuperconductors ............................................... 999
18.4 Magnetic Excitations in Metals and Weakly Coupled Superconductors. . .. . .. . .. . .. . . . . . . . . . . . . . .1001
18.5 Excitations and Superconductive Pairing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .1003
18.6 High Temperature Superconductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . ..1004
18.7 Discussion .. . .. . .. . .. . .. . . . . . . . . . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . .. . .. . ..1023
18.8 Final Remarks . . . .. . .. . . . . . . . . . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . . . . .. . .. . ..1024
References . . . . . . . .. . .. . .. . .. . . . . . . . . . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . .. . .. . .. . ..1024
19 Heavy-Fermion Superconductivity
P. S. Riseborough, G. M. Schmiedeshoff, and J. L. Smith .. . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . .1031
19.1 Overview . . .. . .. . .. . .. . . . . . . . . . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . .. . .. . .. . ..1031
19.2 Introduction . . . . . . . . . . . . .. . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . ..1033
19.3 Properties of the Normal State .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . . . . .. . .. . ..1069
19.4 PropertiesoftheSuperconductingState.........................................................1103
19.5 Heavy Fermion Superconducting Compounds . . . . . . . . . . . .. . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1132
19.6 The Conclusion . . . . . . . . . .. . .. . .. . . . . . . . . . . . . . . . . .. . .. . . . . . . . . . . . . .. . .. . .. . .. . . . . . . . . . .. . .. . .. . . .1140
References . . . . . . . .. . .. . .. . .. . . . . . . . . . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . .. . .. . .. . ..1141
20 Organic Superconductors
M. Lang a nd J. M¨uller . . . .. . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . .. . .. . . . . . . . . .1155
20.1 Introduction . . . . . . . . . . . . .. . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . ..1155
20.2 Characteristics of Organic Charge-Transfer Conductors .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1157
20.3 Normal-State Properties . . . . . . . . . . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . .. . .. . ..1162
20.4 Superconducting-State Properties .. . . . . .. . .. . .. . . . . . . .. . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..1182
20.5 Epilogue . . . . . . . . .. . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. 1212
References . . . . . . . .. . .. . .. . .. . . . . . . . . . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . .. . .. . .. . ..1214
21 Concepts in High Temperature Superconductivity
E.W. Carlson, V. J. Emery, S.A. Kivelson, and D. Orgad .. . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . .. . .. . . .1225
21.1 Introduction . . . . . . . . . . . . .. . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . ..1227
21.2 High Temperature Superconductivity is Hard to Attain .. . . . . . . . . . . . . .. . .. . .. . . . . . . .. . .. . .. . . . . . .1230
21.3 Superconductivity in the Cuprates: General Considerations .. . .. . .. . .. . . . . . . . . . . . . .. . . . . . . . . . . . .1234
21.4 Preview: OurView of the Phase Diagram . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1244
21.5 Quasi-1D Superconductors . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . . . . . . . . .1245
21.6 Quasi-1D Physics in a Dynamical Stripe Array . . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1257
21.7 Electron Fractionalization in D > 1 as a Mechanism of High Temperature Superconductivity . . .1259
21.8 Superconductors with Small Superfluid Density . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . ..1262
21.9 Lessons from Weak Coupling .. . . . . . . . . . . . . . . . .. . .. . .. . . . . . . . . . . . . .. . .. . .. . . . . . . . . . .. . .. . . . . . . . . .1272
21.10 Lessons from Strong Coupling . . . . . . . . . . .. . .. . .. . . . . . . .. . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..1277
Contents XIII
21.11 Lessons from Numerical Studies of Hubbard and Related Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1286
21.12 Doped Antiferromagnets . . . .. . .. . . . . . . . . . . . . . .. . .. . . . . . . .. . .. . . . . . . . . . . . . . .. . .. . . . . . . .. . .. . . . . . .1300
21.13 Stripes and High Temperature Superconductivity . . . . .. . .. . .. . .. . .. . .. . . . . . . . . . . . . .. . .. . .. . .. . ..1310
References . . . . . . . .. . .. . .. . .. . . . . . . . . . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . .. . .. . .. . ..1327
22 A Spin Fluctuation Model for d-Wave Superconductivity
A. V. Chubukov, D. P ines, and J. Schmalian . . . . . . . .. . . . . . . .. . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . ..1349
22.1 Introduction and Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . ..1349
22.2 Spin–Fermion Model . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . .. . . . . .. . . . . .. . . . . . . . . . . . . . . . . .1358
22.3 Summary of Strong-Coupling Theory for Electron–Phonon Pairing . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1363
22.4 Strong-Coupling Approach to Spin–Fermion Interaction . . . . . . . . . .. . .. . .. . . . . . . . . . .. . .. . . . . . . . . .1366
22.5 Fingerprints of Spin Fermion Pairing.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . ..1377
22.6 Comparison with the Experiments on Cuprates . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . . . . . . . .1389
22.7 Conclusions . . .. . .. . .. . .. . . . . . . . . . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . .. . .. . ..1403
22.8 Note Added . . .. . . . . . . . . . . . . . . . . . . .. . .. . . . . . . . . . . .. . . . . . . .. . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. 1405
References . . . . . . . .. . .. . .. . .. . . . . . . . . . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . .. . .. . .. . ..1407
23 Electronic Theory for Superconductivity in High-T
c
Cuprates and Sr
2
RuO
4
D. Manske, I. Eremin, and K. H. Bennemann . . . . . .. . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . ..1415
23.1 Introduction . . . . . . . . . . . . .. . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . ..1416
23.2 Electronic Theory for Hole-Doped and Electron-Doped Cuprates . . . . . . .. . .. . .. . . . . . . .. . . . . . . . . .1428
23.3 Electronic Theory for Ruthenates (Sr
2
RuO
4
). . . . . . . . . . . . . . . . .. . .. . . . . . . . . . . .. . . . . . . .. . .. . . . . . . . . .1451
23.4 ResultsforHole-DopedandElectron-DopedCuprates...........................................1460
23.5 Results for Sr
2
RuO
4
.. . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . .. . .. . . . . . . . . .1485
23.6 Summary and Outlook . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . .. . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . .1496
Appendix...............................................................................................1497
References . . . . . . . .. . .. . .. . .. . . . . . . . . . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . .. . .. . .. . ..1511
24 Superfluid
3
He and the Cuprate Superconductors
A. J. Leggett . . . . . .. . .. . . . .. . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . .. . .. . . . . . . . . .1517
24.1 Introduction: Bose Condensation and Cooper Pairing .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1517
24.2 The Normal State: Is the Fermi-Liquid PictureValid? . .. . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . . . . .. . ..1522
24.3 Response Functions:The MIR Peak in the Cuprates . . .. . .. . .. . .. . .. . . . . .. . . . . .. . .. . . . . . . . . . . . . . .1525
24.4 The Cooper-Paired States of Superfluid
3
He and the Cuprates: General Considerations . . .. . .. . ..1526
24.5 Symmetry of the Order Parameter. . . . . . . . . . . . . . . .. . . . .. . .. . . . . . . . . . . .. . .. . . . . . . . . . . . . . . . . . . .. . . .1531
24.6 Conclusion . . . . . . . . . .. . .. . . . . . . . . . . . . .. . .. . .. . .. . . . . . . .. . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..1534
24.7 Summary. . . . . .. . .. . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . .1534
References . . . . . . . .. . .. . .. . .. . . . . . . . . . .. . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . .. . .. . . . . . . .. . .. . .. . ..1535
Author Index . . . . . . . . . . . .. . .. . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . .. . .. . . . . . . . . .1537
Subject Index . . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . .. . .. . . . . . . . . .1545
List of Contributors
Bennemann, K.H.
Institut f¨ur Theoretische Physik,
Freie Universit¨at Berlin,
Berlin, Germany
khb@physik.fu-berlin.de
Campuzano, J.C.
Dept. of Physics,
University of Illinois at Chicago, USA and
Materials Science Division, Argonne
National Lab., Argonne, USA
jcc@uic.edu
Carlson, E.W.
Department of Physics, Purdue University,
525 Northwestern Avenue
West Lafayette, IN 47907-2036, USA
ewcarlson@physics.purdue.edu
Chubukov, A.V.
University of Wisconsin Dept. of Physics,
1150 University Ave Madison,WI 53706, USA
chubukov@skazka.physics.wisc.edu
Emery, V.J.
Brookhaven National Laboratory,
Department of Physics,
New York, USA
emery@cmth.phy.dnl.gov
Eremin, I.
Institut f¨ur Mathematische Physik,
TU-Braunschweig , Germany
i.eremin@tu-braunschweig.de
Hayden, S.M.
H.H. Wills Physics Laboratory,
University of Bristol, United Kingdom
S.Hayden@bristol.ac.uk
Kirtley, J.B.
IBM Thomas J. Watson Research Center,
P.O. Box 218Yorktown Heights,
NewYork 10598, USA
kirtley@us.ibm.com.
Kivelson, S.A.
Stanford University, Dept. of Physics,
GLAM McCullough Bldg 476
Lomita Mall Stanford University,
Stanford, CA 94305-4045, California, USA
stevek@physics.ucla.edu
Lang, M.
Physik-Institut der
Johann Wolfgang Goethe Universit¨at,
Frankfurt/Main, Germany
michael.lang@physik.uni-frankfurt.de
Leggett, A.J.
Dept. of Physics, University of Illinois,
Illinois, USA
aleggett@uiuc.edu
Manske, D.
Max-Plank Institute for Solid State Research,
Stuttgart, Germany
D.Manske@fkf.mpg.de
M¨uller, J.
Max-Planck Institute for Chemical Physics of Solids,
Dresden, Germany
mueller@cpfs.mpg.de
XVI List of Contributors
Norman,M.R.
Materials Science Division,
Argonne National Laboratory,
Argonne, USA
norman@anl.gov
Orgad, D.
The Hebrew Univ. of Jerusalem,
Racah Institute of Physics, Israel
orgad@phys.huji.ac.il
Ott, H. R.
ETH Z¨urich, Laboratorium f¨ur Festk¨orperphysik,
ETH H¨onggerberg CH-8093, Switzerland
ott@solid.phys.ethz.ch
Pines, D.
LosAlamosNationalLaboratory,
CNLS Mail Stop B258 Los Alamos, NM 87545, USA
pines@santafe.edu.
Randeria, M.
Tata Institute of Fundamental Research,
Mumbai, India
randeria@theory.tifr.res.in
Riseborough, P. S.
Department of Physics,
Polytech University,
New York, USA
prise@poly.edu
Schmalian, J.
Ames Laboratory, Dept. of Physics and Astronomy,
1 Osborn Drive Ames,IA 50011, USA
schmalian@ameslab.gov.
Schmiedeshoff, G.M.
Occidental College, Department of Physics,
California, USA
gms@oxy.edu
Smith, J.L.
National Laboratory Los Alamos,
Nevada, USA
jlsmith@lanl.gov
Tsuei, C.C.
IBM Thomas J. Watson Research Center,
P.O. Box 218Yorktown Heights,
New York 10598, USA
tsuei@watson.ibm.com.
Zasadzinski, J.F.
Illinois Institute of Technology,
Physics Department,
3301 Dearborn, Chicago,
IL 60616, USA
john
zasadzinski@anl.gov
Volume II
Superconductivity:
Novel Superconductors
14 High-T
c
Superconductivity
H.R. Ott ETH Z¨urich, Laboratorium f¨ur Festk¨orperphysik, Switzerland
14.1 Introduction .............................................................................765
14.2 Typical Structural Characteristics ..........................................................767
14.2.1 BaPb
1−x
Bi
x
O
3
,BaPb
1−x
Sb
x
O
3
,BaBi
1−x
K
x
O
3
............................................767
14.2.2CopperOxideSuperconductors.......................................................768
14.2.3Fullerites,Fullerides.................................................................773
14.2.4 MgB
2
..............................................................................774
14.3 Occurrence of Superconductivity ...........................................................774
14.3.1 BaPb
1−x
Bi
x
O
3
,Ba
1−x
K
x
BiO
3
..........................................................774
14.3.2CopperOxides......................................................................775
14.3.3Fullerides..........................................................................777
14.3.4 MgB
2
..............................................................................778
14.4 Physical Properties of Copper Oxides .......................................................778
14.4.1NormalStateProperties..............................................................779
14.4.2Superconductivity...................................................................787
14.4.3CoexistenceofSuperconductivityandMagneticOrder..................................812
14.5 Physical Properties of Non-Cuprate High-T
c
Superconductors .................................813
14.5.1Ba-BasedOxides....................................................................813
14.5.2 C
60
-BasedMaterials.................................................................815
14.5.3 MgB
2
..............................................................................818
14.6 Final Remarks ............................................................................823
References...............................................................................823
14.1 Introduction
The unexpected and really amazing discovery of
J.G.Bednorz and K.A.M¨uller [1],suggesting that cer-
tain copper-oxide compounds enter a superconduct-
ing state at temperatures exceeding 30 K, provoked
an avalanche of research activities worldwide. Early
confirmations of theconjecture[2–4],as well as rapid
progress in further enhancing the critical tempera-
tures T
c
in related materials, i.e., other types of cop-
per oxides,to temperatures above the boiling point of
nitrogen [5,6],pushed research in superconductivity
into the limelight of science and public interest.This
unprecedented development in the field of supercon-
ductivity is best illustrated by plotting the critical
temperature T
c
as a function of time (see Fig. 14.1),
exemplifying the role of the cuprate materials.
Itisthereforenotsurprisingthatreferringtohigh-
T
c
superconductivity, is very often understood as
considering superconductivity of copper oxides only.
This is, however, not quite fair, because other mate-
rials, such as Pb/Bi-type oxides and, subsequent dis-
coveries, such as the doped fullerites or fullerides
and, more recently, MgB
2
, also exhibit superconduc-
766 H.R.Ott
Fig. 14.1. Enhancement of critical temperatures of super-
conductors as function of time.
tivity at amazingly high temperatures. It is for this
reason that in this review, although for the most part
dedicated to the outstanding properties of a vari-
ety of cuprate materials, short overviews of physi-
cal properties related with superconductivity of Ba-
based Bi-oxide perovskites, doped C
60
materials and
the amazing binary compound MgB
2
,arealsoin-
cluded. The class of quaternary borocarbide com-
pounds for which also maximum critical tempera-
tures for superconductivity exceeding 20 K havebeen
reported, will be treated in a special chapter of this
treatise and is therefore not includedin this overview.
The notion of high temperature superconduc-
tivity was introduced by V.L. Ginzburg quite some
time before the essential breakthrough in 1986. Re-
search led by him, concentrating on identifying al-
ternative electron-phonon interactions in solids that
might lead to superconductivity at elevated temper-
atures,started in 1964 and resulted in a compendium
with the title “High Temperature Superconductiv-
ity”, published 1977 in Russian in Moscow. An En-
glish translation of this work appeared 1982 in Lon-
don [7]. Since at present even the highest critical
temperatures that have been achieved, by common
standards still have to be regarded as low tempera-
tures (∼–140
◦
C), we rather use the terminology of
high-T
c
superconductivity in our context.
In spite of substantial efforts in both experimen-
tal and theoretical research,the mysteries behind the
occurrence of superconductivity in cuprate materi-
als up to temperatures exceeding 100 K are still to
be regarded as conspiring to pose one of the major
unsolved problems of contemporary physics. Most
of the physical properties of the Cu oxides have ex-
perimentally been established with a high degree of
reliability and advances in preparing the materials
are such that excuses for the lack of understanding
as being related to spuriouseffects and uncertainties
in materials compositions, homogeneities and im-
purity content can no longer be accepted. However,
it is still not possible to control the critical temper-
ature T
c
for superconductivity of these materials by
suitably tailoring the chemical composition of the
compounds and alloys to the extent that T
c
can be
enhanced at will. This unsatisfactory situation is, at
least partly, due to the fact that no real basic un-
derstanding of the essential processes that lead to
superconductivity in these cuprates at temperatures
far above those for common metals and alloys ex-
ists and therefore no unfailing guidance for the de-
sign and subsequent synthesis of new and promising
materials with even higher critical temperatures is
available.
Simple intuitive approaches forimproving the sit-
uation are made difficult by the sheer chemical com-
plexity, of the known materials, at least when viewed
at the level of conventional standards of condensed
matter physics.The simplest,i.e.,ternary compounds
have to be doped with charge carriers in order to
exhibit metallic conductivity, giving way to super-
conductivity at low temperatures. Most of these su-