Related papers: Superconductivity in Fe and As based compounds: a …
Neutron diffraction has been used to study the lattice and magnetic structures of the insulating and superconducting Rb$_y$Fe$_{1.6+x}$Se$_2$. For the insulating Rb$_{y}$Fe$_{1.6+x}$Se$_2$, neutron polarization analysis and single crystal…
Various properties of underdoped superconducting cuprates, including the momentum-dependent pseudogap opening, indicate a behavior which is neither BCS nor Bose-Einstein condensation (BEC) like. To explain this issue we introduce a two-gap…
A theory of highly correlated layered superconducting materials isapplied for the cuprates. Differently from an independent-electron approximation, their low-energy excitations are approached in terms of auxiliary particles representing…
Superconducting mechanism of cuprates is discussed in the light of the proximity of the Mott insulator. The proximity accompanied by suppression of coherence takes place in an inhomogeneous way in the momentum space in finite-dimensional…
Superconductors are classified by their pairing mechanism and the coupling strength, measured as the ratio of the energy gap to the critical temperature, Tc. We present an extensive comparison of the gap ratios among many single- and…
The cuprates and iron-based high-temperature superconductors share many common features: layered strongly anisotropic crystal structure, strong electronic correlations, interplay between different types of electronic ordering, the intrinsic…
There exists increasing evidence that the phase diagram of the high-transition temperature (Tc) cuprate superconductors is controlled by a quantum critical point. One distinct theoretical proposal is that, with decreasing hole-carrier…
The recently discovered Fe-based superconductor (FeBS) LaFe2As2 seems to break away from an established pattern that doping FeBS beyond 0.2e/Fe destroys superconductivity. LaFe2As2 has an apparent doping of 0.5e, yet superconducts at 12.1…
We report low-temperature heat transport measurements on superconducting iron sulfide FeS with $T_c \approx$ 5 K, which has the same crystal structure and similar electronic band structure to the superconducting iron selenide FeSe. In zero…
Fe-based superconductors have drawn much attention during the last decade due to the finding of superconductivity in materials containing the magnetic element, Fe, and the coexistence of superconductivity & magnetism. Extensive study of the…
A review of high-pressure studies on Fe-pnictide superconductors is given. The pressure effects on the magnetic and superconducting transitions are discussed for different classes of doped and undoped FeAs-compounds, ROFeAs (R = rare…
Significant progress towards a theory of high-temperature superconductivity in cuprates has been achieved via the study of effective one- and three-band Hubbard models. Nevertheless, material-specific predictions, while essential for…
A consistent microscopic theory of pseudogap phenomena and novel Bose-liquid superconductivity (superfluidity) is presented, based on the fact that in high-$T_c$ cuprates and related systems the energy $\varepsilon_A$ of the effective…
By substituting Fe with the 5d-transition metal Pt in BaFe2As2, we have successfully synthesized the superconductors BaFe2-xPtxAs2. The systematic evolution of the lattice constants indicates that the Fe ions were successfully replaced by…
X-ray absorption spectroscopy (XAS) and high resolution X-ray diffraction are combined to study the interplay between electronic and lattice structures in controlling the superconductivity in cuprates with a model charge-compensated…
Layered superconductors have provided some interesting fields in condensed matter physics owing to the low dimensionality of their electronic states. For example, the high-Tc (high transition temperature) cuprates and the Fe-based…
Among the iron-based pnictide superconductors the material KFe$_2$As$_2$ is unusual in that its Fermi surface does not consist of quasi-nested electron and hole pockets. Here we report measurements of the temperature dependent London…
The origin of the high-temperature superconducting state observed in FeSe thin films, whose phase diagram displays no sign of magnetic order, remains a hotly debated topic. Here we investigate whether fluctuations arising due to the…
We measured the in-plane optical conductivity of a nearly optimally doped (Ba,K)Fe2As2 single crystal with Tc = 39.1 K. Upon entering the superconducting state the optical conductivity below ~20 meV vanishes, strongly suggesting a fully…
We have calculated the tunneling conductance of a superconductor-insulator-superconductor junction based on the polaron-bipolaron theory of superconductivity. The predicted incoherent hump features are in quantitative agreement with…