Related papers: Comment on "Unconventional s-wave superconductivit…
We argue that Raman study of Fe-pnictides is a way to unambiguously distinguish between various superconducting gaps proposed for these materials. We show that $A_{1g}$ Raman intensity has a true resonance peak below $2\Delta$ for extended…
The superconducting gap is the fundamental parameter that characterizes the superconducting state, and its symmetry is a direct consequence of the mechanism responsible for Cooper pairing. Here we discuss about angle-resolved photoemission…
(Li0.8Fe0.2)OHFeSe is a newly-discovered intercalated iron-selenide superconductor with a Tc above 40 K, which is much higher than the Tc of bulk FeSe (8 K). Here we report a systematic study of (Li0.8Fe0.2)OHFeSe by low temperature…
A small number of superconductors are believed to exhibit intrinsic spin triplet pairing, and they are often discussed in terms of a simple, $^3$He-like picture where ferromagnetic spin fluctuations provide the "glue". However, in some…
Vortices are topological defects of type-II superconductors in an external magnetic field. In a similar fashion to a quantum anomalous Hall insulator, quantum anomalous vortex (QAV) spontaneously nucleates due to orbital-and-spin exchange…
This paper explores the potential for spin-triplet superconductivity in molecular beam epitaxy grown PbTe/SnTe semiconductor heterostructures. We present convincing evidence for spin-triplet pairing by soft point-contact spectroscopy…
To elucidate the pairing states in Fe-based superconductors, we perform careful calculation of the dynamical spin susceptibility $\chi^S(q, \omega)$ at very low temperatures ($T \sim 1$ meV). The feedback effect on both the self-energy and…
We have performed soft x-ray and ultrahigh-resolution laser-excited photoemission measurements on tetragonal FeSe, which was recently identified as a superconductor. Energy dependent study of valence band is compared to band structure…
Several angle resolved photoemission spectroscopy (ARPES) studies reveal a poorly nested Fermi surface of LiFeAs, far away from a spin density wave instability, and clear-cut superconducting gap anisotropies. On the other hand a very…
FeSe is argued as a superconductor in the Bardeen-Cooper-Schrieffer Bose-Einstein-condensation crossover regime where the superconducting-gap size and the superconducting transition temperature Tc are comparable to the Fermi energy. In this…
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,…
Fe K-edge and Se K-edge x-ray absorption near edge structure (XANES) measurements are used to study FeSe$_{1-x}$Te$_{x}$ electronic structure of chalcogenides. An intense Fe K-edge pre-edge peak due to Fe 1s$\to$3d (and admixed Se/Te $p$…
Electronic spectra of typical single FeSe layer superconductors obtained from ARPES data reveal several puzzles: what is the origin of shallow and the so called "replica" bands near M-point and why the hole-like Fermi surfaces near…
This review discusses the main experiments and theoretical views related to observation of high-temperature superconductivity in intercalated FeSe compounds and single layer films of FeSe on substrates like SrTiO_3. We consider in detail…
The low energy band structure and Fermi surface of the newly discovered superconductor, AxFe2Se2 (A=K,Cs), have been studied by angle-resolved photoemission spectroscopy. Compared with iron pnictide superconductors, AxFe2Se2 (A=K,Cs) is the…
A brief review of optical and Raman studies on the Fe-based superconductors is given, with special emphasis on the competing phenomenon in this system. Optical investigations on ReFeAsO (Re=rare-earth element) and AFe$_2$As$_2$…
We show that quasiparticle interference (QPI) due to omnipresent weak impurities and probed by Fourier transform scanning tunneling microscopy and spectroscopy acts as a direct experimental probe of bulk odd-frequency superconducting…
Recent STM experiments and theoretical considerations have highlighted the role of interaction-driven orbital selectivity in FeSe, and its role in generating the extremely anisotropic superconducting gap structure in this material. We study…
Emergent electronic phenomena in iron-based superconductors have been at the forefront of condensed matter physics for more than a decade. Much has been learned about the origin and intertwined roles of ordered phases, including nematicity,…
Fe-based superconductors were discovered in 2008. This discovery with T$_c$ values up to 56 K, generated a new belief in the field of superconductivity. Till its discovery, high temperature superconductivity in cuprates, created a prejudice…