Related papers: Isotropic superconducting gaps with enhanced pairi…
We determine the anisotropy of the spin fluctuation induced pairing gap on the Fermi surface of the FeAs based superconductors as function of the exchange and Hund's coupling $J_{H}$. We find that for sufficiently large $J_{H}$, nearly…
For the iron-based high $T_c$ superconductor LaFeAsO$_{1-x}$F$_x$, we construct a minimal model, where all of the five Fe $d$ bands turn out to be involved. We then investigate the origin of superconductivity with a five-band random-phase…
We study whether Fermi-surface (FS) nesting can give rise to high-temperature superconductivity in iron pnictides. Starting with ab initio construction of an effective four-orbital model, we employ the fluctuation-exchange approximation to…
We model a single layer of heavily electron-doped FeSe by spin-1/2 moments over a square lattice of iron atoms that include the 3d xz and 3d yz orbitals, at strong on-site Coulomb repulsion. Above half filling, we find emergent hole bands…
We use high resolution angle resolved photoemission spectroscopy and density functional theory with experimentally obtained crystal structure parameters to study the electronic properties of CaKFe4As4. In contrast to related CaFe2As2…
Among numerous hypotheses, recently proposed to explain superconductivity in iron-based superconductors [1-9], many consider Fermi surface (FS) nesting [2, 4, 8, 10] and dimensionality [4, 9] as important contributors. Precise determination…
High-temperature superconductivity in iron-arsenic materials (pnictides) near an antiferromagnetic phase raises the possibility of spin-fluctuation-mediated pairing. However, the interplay between antiferromagnetic fluctuations and…
The iron-based superconductors are characterized by multiple-orbital physics where all the five Fe 3$d$ orbitals get involved. The multiple-orbital nature gives rise to various novel phenomena like orbital-selective Mott transition,…
The interplay of nontrivial topology and superconductivity in condensed matter physics gives rise to exotic phenomena. However, materials are extremely rare where it is possible to explore the full details of the superconducting pairing.…
We have performed high resolution angle-resolved photoemission measurements on superconducting electron-doped NaFe$_{0.95}$Co$_{0.05}$As ($T_{c}\sim$18 K). We observed a hole-like Fermi surface around the zone center and two electron-like…
Topological superconductors should be able to provide essential ingredients for quantum computing, but are very challenging to realize. Spin-orbit interaction in iron-based superconductors opens the energy gap between the $p$-states of…
In the underdoped high temperature superconductors, instead of a complete Fermi surface above Tc, only disconnected Fermi arcs appear, separated by regions that still exhibit an energy gap. We show that in this pseudogap phase, the…
We report a distinct experimental approach to point-contact Andreev reflection spectroscopy with diagnostic capability via a unique design of nano-scale normal metal/superconductor devices with excellent thermo-mechanical stability, and…
The iron-pnictide superconductors have a layered structureformed by stacks of FeAs planes from which the superconductivity originates. Given the multiband and quasi three-dimensional \cite{3D_SC} (3D) electronic structure of these…
I review theoretical ideas and implications of experiments for the gap structure and symmetry of the Fe-based superconductors. Unlike any other class of unconventional superconductors, one has in these systems the possibility to tune the…
Unconventional superconductivity is commonly linked to electronic pairing mechanisms, since it is believed that the conventional electron-phonon interaction (EPI) cannot cause sign-changing superconducting gap symmetries. Here, we show that…
We measured the electronic-structure of FeSe_xTe_1-x above and below Tc. In the normal state we find multiple bands with remarkably small values for the Fermi energy, E_F. Yet,below Tc we find a superconducting gap, Delta, that is…
We analyze antiferromagnetism and superconductivity in novel $Fe-$based superconductors within the itinerant model of small electron and hole pockets near $(0,0)$ and $(\pi,\pi)$. We argue that the effective interactions in both channels…
In exotic superconductors including high-$T_c$ copper-oxides, the interactions mediating electron Cooper-pairing are widely considered to have a magnetic rather than the conventional electron-phonon origin. Interest in such exotic pairing…
In the recently discovered kagome superconductor AV3Sb5 (A = K, Rb, and Cs), superconductivity is intertwined with an unconventional charge density wave order. The pairing symmetry remains elusive owing to the lack of direct measurement of…