Iron-based Superconductors: Materials, Properties and Mechanisms

554 Pages·2012·44.266 MB·\554

by  Nan Lin Wang (Editor), Hideo Hosono (Editor), Pengcheng Dai (Editor)

“In February 2008, Dr. Hosono and coworkers broke the striking news that they had found
a new superconductor, LaFeAsO F with T = 26 K. This news immediately spread out in
1–x x c
the world, and soon after its T was increased to 55 K. This breakthrough rekindled the
c edited by
superconducting research, which was in a state of dying fire after the discovery of Cu I
oxide superconductor in 1988 and MgB in 2001. This book presents a comprehensive R Nan-Lin Wang
2
review on the present status of Fe-pnictide superconductors, including the material, a
O Hideo Hosono
variety of experimental results (photoemission, neutron scattering, NMR, etc.), theory,
and so forth.” N Pengcheng Dai
Dr. Jun Akimitsu
Aoyama Gakuin University, Japan -
B
“The timely appearance of the first review volume on iron-based superconductors will
greatly promote research on this exciting subject. The authors’ undisputable expertise A
guarantees its lasting value.”
S
Prof. Lu Yu
Chinese Academy of Sciences, China
E
“The balance between early and recent developments establishes this book as an D
excellent source of information for both beginners and advanced researchers.”

Prof. Elbio Ruben Dagotto S
University of Tennessee, USA
U
Iron-based superconductors, compared with cuprate superconductors, are much more
P
flexible and have a large variety of parent compounds. From the point of view of
fundamental physics, they have properties that are more amenable to band structure E
calculations. This allows a quantitative comparison with experiments. In addition, iron-
R
based superconductors have intrinsic properties favorable for certain applications, such
as inertness to impurities, large and isotropic upper critical fields, and strong grain C
boundaries. This book reviews the progress made in this fascinating field. The contributors
O
are leading experts in their fields. The text is a good guide for understanding materials,
physical properties, and superconductivity mechanism. Students and beginners will find
N
it quite useful for familiarizing themselves with the recent progress made in this field.
D
Nan-Lin Wang is a professor and group leader at the Institute of Physics,
Chinese Academy of Sciences, China. He leads a group that explores novel U
superconducting and other strongly correlated materials, grows single
C
crystals, and investigates their electronic properties, particularly with optical
spectroscopic techniques. T
O MATERIALS, PROPERTIES, AND MECHANISMS
Hideo Hosono is a professor at Frontier Research Center and Materials and
Structures Laboratory, Tokyo Institute of Technology, Japan. His major concern R IRON-BASED
is to create novel electro-active materials, including superconductors based
S
on his own idea. He is a pioneer of transparent oxide semiconductors. Iron-
based superconductors were discovered by his group in 2006–2008.
SUPERCONDUCTORS
Pengcheng Dai is a professor of physics at the University of Tennessee-
Knoxville, USA, and the Institute of Physics, Chinese Academy of Sciences. Wang
His interest is to use neutron scattering as a probe to study correlated
Hosono
electron materials, including high-temperature superconductors.
Dai
V149
ISBN-13 978-981-4303-22-4

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Version Date: 20121207
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October10,2012 9:37 PSPBook-9inx6in 00-Wang–prelims
Contents
Preface xiii
1 Iron-BasedSuperconductors:DiscoveryandProgress
inMaterials 1
HideoHosono
1.1 Introduction 1
1.2 SmallHistoryonDiscoveryandProgressinParent
Materials 3
1.3 CrystalStructureofParentMaterials 6
1.3.1 1111-TypeMaterials(LnFePnO,Ln:
Lanthanide) 6
1.3.2 122-TypeMaterials(AeFe Pn ,Ae:Alkaline
2 2
EarthorEu) 9
1.3.3 111-TypeMaterials(AFePn,A:AlkaliMetal) 10
1.3.4 11-TypeMaterials(Fe1+xSe) 10
1.3.5 Homologous-TypeMaterials:
(Fe2As2)(Aen+1MmOy) 10
1.4 ParentMaterialandSuperconductivity 11
1.4.1 DopingEffect 11
1.4.1.1 The1111-type 12
1.4.1.2 The122-type 15
1.4.2 LocalStructureandT 20
c
1.5 UniqueCharacteristicsofFeSCs 23
1.5.1 Multi-BandNatureofFe3d 23
1.5.2 ParentMaterial:AntiferromagneticMetal 24
1.5.3 ImpurityRobustT 25
c
1.5.4 LargeCriticalFieldandSmallAnisotropy 25
1.5.5 AdvantageousGrainBoundaryNature 26
October10,2012 9:37 PSPBook-9inx6in 00-Wang–prelims
vi Contents
1.6 SingleCrystal 27
1.6.1 Growthof1111-TypeCrystals 27
1.6.2 Growthofthe122-TypeCrystals 29
1.6.3 CharacteristicsofaSingleCrystal 30
1.7 ThinFilm 32
1.7.1 1111-TypeCompounds 32
1.7.2 122-TypeCompounds 35
1.7.3 11-TypeCompounds 38
1.8 SummaryandRelevantNewSuperconductors 40
2 SynthesisandPhysicalPropertiesoftheNew
PotassiumIronSelenideSuperconductorK Fe Se 53
0.80 1.76 2
R.Hu,E.D.Mun,D.H.Ryan,K.Cho,H.Kim,H.Hodovanets,
W.E.Straszheim,M.A.Tanatar,R.Prozorov,
W.N.Rowan-Weetaluktuk,J.M.Cadogan,
M.M.Altarawneh,C.H.Mielke,V.S.Zapf,S.L.Bud’ko,
andP.C.Canfield
2.1 Introduction 54
2.2 ExperimentalMethods 55
2.3 CrystalGrowthandStoichiometry 57
2.4 PhysicalPropertiesofSingleCrystalsofK0.80Fe1.76Se2 59
2.4.1 TransportandThermodynamicProperties 59
2.4.2 LondonPenetrationDepthand
Magneto-OpticalImaging 64
2.4.3 AnisotropicH (T) 66
c2
2.4.4 57FeMo¨ssbauerSpectroscopy 71
2.4.5 PhaseSeparationandPossible
SuperconductingAerogel 79
2.5 Summary 80
3 Angle-ResolvedPhotoemissionSpectroscopyofIron
Pnictides 89
TakafumiSato,PierreRichard,KosukeNakayama,
TakashiTakahashi,andHongDing
3.1 Introduction 90
3.1.1 PrincipleofARPES 91
3.2 ExperimentalResults 93
3.2.1 FermiSurfaceandPairingSymmetry 93
3.2.1.1 Hole-dopedsystem 93
3.2.1.2 Electron-dopedsystem 104
October10,2012 9:37 PSPBook-9inx6in 00-Wang–prelims
Contents vii
3.2.2 Many-BodyInteractions 108
3.2.3 ParentCompound 112
3.3 ConcludingRemarksandSummary 115
4 QuantumOscillationsinIronPnictide
Superconductors 125
SuchitraE.Sebastian
4.1 QuantumOscillations 126
4.1.1 AngularDependence 128
4.1.1.1 Fermisurfacegeometry 128
4.1.1.2 Spinsplitting 128
4.2 MagneticFieldDependence 129
4.3 TemperatureDependence 130
4.4 IronPnictideSuperconductors 131
4.5 QuantumOscillationsinAntiferromagneticParent
IronPnictides 131
4.5.1 FermiSurfaceGeometry:Nonmagneticand
AntiferromagneticBandStructureCalculations 134
4.5.2 ExperimentalComparisonwithBandStructure 137
4.5.3 DiracNodes 141
4.6 QuantumOscillationsinOverdopedParamagnetic
IronPnictides 142
4.6.1 Quasi-NestingofHoleandElectronCylinders 144
4.7 CupratesandIronPnictides:ElectronicStructure
Comparison 146
4.7.1 EnhancementinLindhardFunctionin
PnictidesandCuprates 147
4.7.2 QuantumCriticalPointunderSuperconducting
Dome 149
4.8 Conclusion 152
5 OpticalInvestigationonIron-BasedSuperconductors 161
Nan-LinWangandZhi-GuoChen
5.1 Introduction 161
5.2 IntroductionAboutOpticalPropertiesofSolids 164
5.2.1 OpticalConstants 164
5.2.2 InterbandandIntrabandExcitations 166
5.2.3 DrudeModelandDrude-LorentzModel 168
5.2.4 ExtendedDrudeModel 170
October10,2012 9:37 PSPBook-9inx6in 00-Wang–prelims
viii Contents
5.2.5 SumRules 172
5.2.6 OpticalResponseofBrokenSymmetryStates
ofMetals 174
5.3 OpticalStudiesontheParentCompounds 176
5.3.1 SpinDensityWaveGapinFeAs-Based
Compounds 177
5.3.2 AbsenceofSDWGapinFeTe1+x 182
5.3.3 FullyLocalizedFe3dElectronsinK0.8Fe1.6Se2 184
5.4 Multi-Componentsvs.ExtendedDrudeModel
AnalysisofOpticalConductivity 186
5.5 ElectronCorrelationsinthe
Fe-Pnictides/Chalcogenides 192
5.5.1 KineticEnergyReductionbyElectron
Correlations 192
5.5.2 EffectofHund’sCoupling 196
5.6 AnisotropicChargeDynamics 201
5.6.1 c-AxisOpticalPropertiesinParent
Compounds 201
5.6.2 AnisotropicOpticalPropertieswithin
ab-Plane 204
5.6.3 c-AxisOpticalPropertiesofSuperconducting
Compounds 209
5.7 OpticalPropertiesofIron-BasedSuperconductors
BelowT 214
c
5.7.1 ProbingtheSuperconductingEnergyGaps 214
5.7.2 JosephsonCouplingPlasmoninKxFe2−ySe2 223
5.7.3 Superconductivity-InducedSpectralWeight
Transfer 226
5.7.4 CoherentPeakBelowT ProbedbyTHz
c
Spectroscopy 230
6 AntiferromagneticSpinFluctuationsintheFe-Based
Superconductors 243
ShiliangLiandPengchengDai
6.1 Introduction 244
6.2 AntiferromagnetisminParentCompounds 246
6.2.1 Long-RangeAntiferromagneticOrder 246
6.2.2 SpinWaves 249
6.2.3 DestructionofAntiferromagneticOrder 253
October10,2012 9:37 PSPBook-9inx6in 00-Wang–prelims
Contents ix
6.3 MagneticExcitationsintheSuperconductingState 256
6.3.1 MagneticResonance 257
6.3.2 FieldEffectonMagneticResonance 261
6.3.3 Field-InducedMagnetization 264
6.4 MagneticExcitationsintheNormalState 264
6.4.1 In-PlaneAnisotropyinthe“122”System 264
6.4.2 IncommensurateMagneticExcitationsinthe
“11”System 265
6.5 Conclusion 268
7 ReviewofNMRStudiesonIron-Based
Superconductors 275
KenjiIshidaandYusukeNakai
7.1 Introduction 275
7.2 NMRBasics 276
7.2.1 NMRHamiltonian 276
7.2.2 KnightShiftandNuclearSpin-Lattice
RelaxationRateinMetals 278
7.2.3 KnightShiftandNuclearSpin-Lattice
RelaxationRateintheSuperconductingState 281
7.3 NMRExperimentalResultsonIron-Based
Superconductors 287
7.3.1 LaFeAs(O1−xFx)andLaFeAsO1−δwith“1111”
Structure 287
7.3.1.1 LaFeAsO:parentcompound 288
7.3.1.2 NormalstateofLaFeAs(O1−xFx)and
LaFeAsO1−δ 291
7.3.1.3 Superconductingstateof
LaFeAs(O1−xFx)andLaFeAsO1−δ 299
7.3.2 NMRStudyin“122”System 305
7.3.2.1 BaFe As 307
2 2
7.3.2.2 NMRinthenormalstateof
BaFe2(As1−xPx)2 313
7.3.2.3 NMRinthenormalstateof
Ba(Fe1−xCox)2As2 319
7.3.2.4 NMRinthenormalstateof
(Ba1−xKx)Fe2As2 323
7.3.2.5 NMRresultsonthesuperconducting
stateof“122”compounds 325