edited by Nan-Lin Wang Hideo Hosono Pengcheng Dai MATERIALS, PROPERTIES, AND MECHANISMS IRON-BASED SUPERCONDUCTORS

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1 edited by " Nan-Lin Wang Hideo Hosono Pengcheng Dai MATERIALS, PROPERTIES, AND MECHANISMS IRON-BASED SUPERCONDUCTORS Pan Stanford Publishing

2 Contents Preface xiii 1 Iron-Based Superconductors: Discovery and Progress in Materials 1 Hideo Hosono 1.1 Introduction Small History on Discovery and Progress in Parent Materials Crystal Structure of Parent Materials Type Materials (LnFePnO, Ln: Lanthanide) Type Materials (AeFe2Pn2, Ae: Alkaline Earth or Eu) Ill-Type Materials (AFePn, A: Alkali Metal) Type Materials (Fe1+xSe] Homologous-Type Materials: (Fe2As2)(Aen+1MmOy) Parent Material and Superconductivity Doping Effect Thellll-type Thel22-type Local Structure and Tc Unique Characteristics of FeSCs Multi-Band Nature of Fe3d Parent Material: Antiferromagnetic Metal Impurity Robust Tc Large Critical Field and Small Anisotropy Advantageous Grain Boundary Nature 26

3 vi I Contents 1.6 Single Crystal Growth of 1111-Type Crystals Growth of the 122-Type Crystals Characteristics of a Single Crystal Thin Film Type Compounds Type Compounds Type Compounds Summary and Relevant New Superconductors 40 2 Synthesis and Physical Properties ofthe New Potassium Iron Selenide Superconductor Ko.soFeueSez 53 R. Hu, E. D. Man, 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. Zap/, S. L Bud'ko, and P. C. Canfield 2.1 Introduction Experimental Methods Crystal Growth and Stoichiometry Physical Properties of Single Crystals of K0.8oFei.76Se Transport and Thermodynamic Properties London Penetration Depth and Magneto-Optical Imaging Anisotropic Hc2{T) Fe Mossbauer Spectroscopy Phase Separation and Possible Superconducting Aerogel Summary 80 3 Angle-Resolved Photoemission Spectroscopy of Iron Pnictides Takafumi Sato, Pierre Richard, Kosuke Nakayama, Takashi Takahashi, and Hong Ding Introduction Principle of ARPES Experimental Results Fermi Surface and Pairing Symmetry Hole-doped system Electron-doped system 104

4 Contents Many-Body Interactions Parent Compound Concluding Remarks and Summary Quantum Oscillations in Iron Pnictide Superconductors 125 Suchitra E. Sebastian 4.1 Quantum Oscillations Angular Dependence Fermi surface geometry Spin splitting Magnetic Field Dependence Temperature Dependence Iron Pnictide Superconductors Quantum Oscillations in Antiferromagnetic Parent Iron Pnictides Fermi Surface Geometry: Nonmagnetic and Antiferromagnetic Band Structure Calculations Experimental Comparison with Band Structure Dirac Nodes Quantum Oscillations in Overdoped Paramagnetic Iron Pnictides Quasi-Nesting of Hole and Electron Cylinders Cuprates and Iron Pnictides: Electronic Structure Comparison Enhancement in Lindhard Function in Pnictides and Cuprates Quantum Critical Point under Superconducting Dome Conclusion Optical Investigation on Iron-Based Superconductors 161 Nan-Lin Wang and Zhi-Guo Chen 5.1 Introduction Introduction About Optical Properties of Solids Optical Constants Interband and Intraband Excitations Drude Model and Drude-Lorentz Model Extended Drude Model 170

5 viii Contents Sum Rules Optical Response of Broken Symmetry States of Metals Optical Studies on the Parent Compounds Spin Density Wave Gap in FeAs-Based Compounds Absence ofsdw Gap in FeTe1+x Fully Localized Fe 3d Electrons in K0.sFei.6Se Multi-Components vs. Extended Drude Model Analysis of Optical Conductivity Electron Correlations in the Fe-Pnictides/Chalcogenides Kinetic Energy Reduction by Electron Correlations Effect of Hund's Coupling Anisotropic Charge Dynamics c-axis Optical Properties in Parent Compounds Anisotropic Optical Properties within afa-plane c-axis Optical Properties of Superconducting Compounds Optical Properties of Iron-Based Superconductors Below Tc Probing the Superconducting Energy Gaps Josephson Coupling Plasmon in KxFe2_),Se Superconductivity-Induced Spectral Weight Transfer Coherent Peak Below Tc Probed by THz Spectroscopy Antiferromagnetic Spin Fluctuations in the Fe-Based Superconductors 243 Shiliang Li and Pengcheng Dai 6.1 Introduction Antiferromagnetism in Parent Compounds Long-Range Antiferromagnetic Order Spin Waves Destruction of Antiferromagnetic Order 253

6 Contents ix 6.3 Magnetic Excitations in the Superconducting State Magnetic Resonance Field Effect on Magnetic Resonance Field-Induced Magnetization Magnetic Excitations in the Normal State In-Plane Anisotropy in the "122" System Incommensurate Magnetic Excitations in the "11" System Conclusion Review of NMR Studies on Iron-Based Superconductors 275 Kenji Ishida and Yusuke Nakai 7.1 Introduction NMR Basics NMR Hamiltonian Knight Shift and Nuclear Spin-Lattice Relaxation Rate in Metals Knight Shift and Nuclear Spin-Lattice Relaxation Rate in the Superconducting State NMR Experimental Results on Iron-Based Superconductors LaFeAs(Oi_xFx] and LaFeAsO^ with "1111" Structure LaFeAsO: parent compound Normal state of LaFeAstOi-xF*) and LaFeAsOi_{ Superconducting state of LaFeAs(Oi_xFx)andLaFeAsOi_« NMR Study in "122" System BaFe2As NMR in the normal state of BaFe2(Asi_xPx) NMR in the normal state of Ba(Fei_xCox)2As NMR in the normal state of CBai_xKx)Fe2Asz NMR results on the superconducting state of "122" compounds 325

7 x Contents NMR Study in "111" System, LiFeAs and NaFeAs NMR Study in "11" System, FeSe NMR Study in KxFe2-ySe Summary Material Specific Model Hamiltonians and Analysis on the Pairing Mechanism 357 Kazuhiko Kuroki 8.1 Introduction Model Hamiltonian Construction The Band Structure Electron-Electron Interactions Spin Fluctuations and Antiferromagnetism Random Phase Approximation Electron-Hole Interaction Antiferromagnetism in the Parent Compound Superconductivity General Theory on Fluctuation Mediated Pairing Spin Fluctuation Mediated Pairing Orbital Fluctuation Mediated Pairing Theoretical Proposals for the Detection of the Pairing State Based on the Effective Multiorbital Hamiltonian Material Dependence Some Experimental Observations Lattice Structure Dependence of the Band Structure and the Electron-Electron Interactions Pnictogen height Bond angle Three dimensionality Material Dependence of the Spin Fluctuations and Superconductivity Lattice structure dependence 400

8 Spin Contents xi Doping dependence Effect ofthe three dimensionality Concluding Remarks and Perspectives The Antiferromagnetic Phase of Iron-Based Superconductors: An Itinerant Approach 431 Johannes Knolle and Hya Eremin 9.1 Introduction A Primer: Single-Band Hubbard Model Magnetic Order in Ferropnictides Magnetic Frustration Lifting the Magnetic Ground State Degeneracy at TN Ising Nematic Order Above TN Spin Waves in Itinerant Multiorbital Systems Multiorbital Models Wave Theory Accidental Collective Modes in Itinerant Frustrated Antiferromagnets Two Orbital Model: Orbital versus Excitonic Scenario Comparison to Experiments Discussion and Conclusion Magnetism in Parent Compounds of Iron-Based Superconductors 473 Jiangping Hit 10.1 Introduction Experimental Results on the Parent Compounds of Iron-Based Superconductors Results on Iron-Pnictides Results on Iron-Chalcogenides Electronic Structures and Resistivity Anisotropy Theoretical Models Results offirst Principle Electronic Structure Calculation Effective Magnetic Exchange Models for Iron-Pnictides 485

9 xii Contents Effective Magnetic Exchange Models for Iron-Chalcogenides FeTe Ao.8Fei.6Se A Unified Minimum Magnetic Exchange Model For Iron-Based Superconductors Electronic Nematism and the Interplay Between Lattice, Spin and Orbital Discussion 507 Index 513