The Iron Pnictide Superconductors: An Introduction and Overview

1. "Fe based Superconductors: Materials, phase diagrams, and spectroscopy"

(i) Overview on Materials and General Phase Diagrams of Fe based Superconductors
(ii) Low energy probes of the physical properties of Fe based superconductors
(iii) Electron spectroscopy on Fe based superconductors
(iv) Aspects of STM on Fe based superconductors
(v) Experimental Studies of Nematic Order in Fe based SC

written by Prof. Dr. Bernd Büchner
Institute for Solid State Research
Helmholtzstraße 20
01171 Dresden, Germany

2. "Modeling many-body physics in Fe-superconductors and other multi-orbital materials with the Slave-Spin mean-field: Mott and Hund's physics"
(i) Interactions and correlations. Single-particle vs many-body physics. Chemistry of correlated materials.
(ii) Introduction to the Slave-spin method. Auxiliary variables. Mean-field decoupling< (iii) The Mott-Hubbard transition. Strongly Correlated Fermi-liquids
(iv) Multi-orbital Hubbard models. Hund's coupling. Mott transition in a multi-orbital context.
(v) Slave-spin mean-field for realistic correlated band structures. Mott and Hund's physics in Fe-based pnictides. Comparison with experiments.

written by

Prof. Massimo Capone
Scuola Internazionale Superiore di Studi Avanzati
via Bonomea, 265 Trieste ITALY
Dr. Luca de' Medici
European Synchrotron Radiation Facility (ESRF)
Grenoble, France

3. "Cooper-pairing, magnetic frustration, and spin fluctuations in iron-based superconductors"
(i) Leading instabilities in ferropnictides: weak-coupling analysis, RPA and renormalization group study, comparison to cuprates.
(ii) Magnetic order: manifold of the ground states, C2 and C4 phases, selection of the magnetic states, role of spin orbit coupling.
(ii

i) Spin excitations in the magnetic state within itinerant description: magnetic anisotropy of the excitations, coexistence with the superconducting state.
(iv) SC state: multiband effects beyond simple s+- (nodal structure, role of additional hole pockets with difference orbital structure), role of 'simple' disorder on Tc, quasiparticle interference.

written by Prof. Dr. Ilya Eremin
Ruhr-Universität Bochum
Universitätstraße 150
44801 Bochum, Germany

4. "Nematic order and fluctuations in iron based superconductors"
(i) Summary of collective field theories of magnetism
a) Order-parameter field theory from a microscopic Hamiltonian
b) Solution of the field theory (introduction to the large-N approach)
(ii) Emergent nematic order in iron based systems
a) Order-parameter theory of stripe magnetic order
b) Analysis of the large-N limit and Isin

g-nematicity
(iii) Phase diagram and observables I
a) Analysis of the phase diagram
b) Nematic susceptibility and elastic properties
(iv) Phase diagram and observables II
a) Anisotropy of the resistivity
b) Raman scattering and nematic susceptibility
(v) Impact on superconductivity
a) Raman resonance mode in the superconducting state
b) Nematic fluctuations and pairing.

written by Prof. Dr. Jörg Schmalian
Karlsruhe Institut für Technologie
Wolfgang-Gaede-Str. 1
D-76131 Karlsruhe, Germany