Related papers: Anomalous Magnetic Susceptibility in Iron Pnictide…
Through a systematic high resolution angle-resolved photoemission study of the iron pnictide compounds (Ba,Sr)Fe$_2$As$_2$, we show that the electronic structures of these compounds are significantly reconstructed across the spin density…
Using Monte Carlo simulations with a tunable uniaxial strain, for the first time the nematic susceptibility of a model for the pnictides is calculated. The results are in good agreement with the experiments by J-H. Chu {\it et al.}, Science…
Strange metals appear in a wide range of correlated materials. Electronic localization-delocalization and the expected loss of quasiparticles characterize beyond-Landau metallic quantum critical points and the associated strange metals.…
Nematic order in the iron-based superconductors is closely tied to a lattice distortion and a structural transition from tetragonal to orthorhombic symmetry. External stress of the appropriate symmetry acts as a conjugate field of the…
Frustrated Kondo spin lattice (KSL) systems away from the antiferromagnetic (AFM) ground state have been found to display strange metal behaviour. A signature of strange metals in correlated systems is large Nernst response.…
We examine electronic states of antiferromagnetic phase in iron pnictides by mean-field calculations of the optical conductivity. We find that a five-band model exhibiting a small magnetic moment, inconsistent with the first-principles…
The doping dependence of spin excitations in Ba(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$ is studied based on a two-orbital model under RPA approximation. The interplay between the spin-density-wave (SDW) and superconductivity (SC) is considered in…
Anomalous metals are observed in numerous experiments on disordered two-dimensional systems proximate to superconductivity. A characteristic feature of an anomalous metal is that its low temperature conductivity has a weakly temperature…
Similar to the cuprate high TC superconductors, the iron pnictide superconductors also lie in close proximity to a magnetically ordered phase. A central debate concerning the superconducting mechanism is whether the local magnetic moments…
The extent to which quantum criticality drives the physics of iron pnictides is a central question in the field. Earlier theoretical considerations were based on an effective field theory, and the proposed realization in P-doped iron…
One of the central questions about the iron pnictides concerns the extent to which their electrons are strongly correlated. Here we address this issue through the phenomenology of the charge transport and dynamics, single-electron…
We examine the appearance of a spin density wave in the FeAs parent compounds due to an excitonic instability. Using a realistic four-band model, we show that the magnetic state depends very sensitively upon the details of the band…
In the usual Fock-and Darwin-formalism with parabolic potential characterized by the confining energy $\eps_o := \hbar\omega_o= 3.37$ meV, but including explicitly also the Zeeman coupling between spin and magnetic field, we study the…
We present $^{57}$Fe-NMR measurements of the novel normal and superconducting-state characteristics of the iron-arsenide superconductor Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ ($T_c$ = 38 K). In the normal state, the measured Knight shift and…
Doping dependence of the spin fluctuations and the electron correlations in the effective five-band Hubbard model for iron pnictides is investigated using the fluctuation-exchange approximation. For a moderate hole doping, we find a…
The concept of an electronically-driven breaking of the rotational symmetry of a crystal, without involving magnetic order, has found experimental support in several systems, from semiconductor heterostructures and ruthenates, to cuprate…
This article reviews the NMR and NQR studies on iron-based high-temperature superconductors by the IOP/Okayama group. It was found that the electron pairs in the superconducting state are in the spin-singlet state with multiple fully-opened…
We investigate the electronic properties of an exemplar transition metal impurity in an insulator, with the goal of accurately describing strongly correlated, defect states. We consider iron in aluminum nitride, a material of interest for…
It is demonstrated that novel spin frustration can be induced in ferromagnets with nonuniform Land\'{e} $g$-factors. The frustrated state is characterized by a mutual interplay of typical ferromagnetic (FM) and antiferromagnetic (AF)…
We have studied the interplay of magnetism and superconductivity in LaFeAsO$_{1-x}$F$_x$ and Ca(Fe$_{1-x}$Co$_x$)$_2$As$_2$. While antiferromagnetic spin density wave formation is suppressed and superconductivity evolves, all samples show a…