Related papers: Bulk and surface Dirac states accompanied by two s…
Topological Dirac semimetals (TDSs) exhibit bulk Dirac cones protected by time reversal and crystal symmetry, as well as surface states originating from non-trivial topology. While there is a manifold possible onset of superconducting order…
We performed $^{77}$Se-NMR measurements on FeSe$_{1-x}$S$_x$, ($x$ = 0.12) up to 3.0 GPa at an applied magnetic field of 6.02 T, and found that the superconducting (SC) phase exhibits a remarkable double-dome structure in the…
Superconducting and topological states are two distinct quantum states of matter. Superconductors with topologically nontrivial electronic states provide a platform to study the interplay between them. Recent study revealed that a bulk…
We theoretically study intrinsic superconductivity in doped Dirac semimetals. Dirac semimetals host bulk Dirac points, which are formed by doubly degenerate bands, so the Hamiltonian is described by a $4 \times 4$ matrix and six types of…
The superconducting transition temperature, $T_{\rm{c}}$, of FeSe can be significantly enhanced several-fold by applying pressure, electron doping, intercalating spacing layer, and reducing dimensionality. Various ordered electronic phases,…
High-temperature superconductivity and a wide variety of exotic superconducting states discovered in FeSe-based materials have been at the frontier of research on condensed matter physics over the past decade. Unique properties originating…
The coexistence of topological bands around the Fermi level ($E_F$) and superconductivity provides a fundamental platform for exploring their interplay. However, few materials inherently display both properties. In this study, we…
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.…
The BCS-BEC crossover from strongly overlapping Cooper pairs to non-overlapping composite bosons in the strong coupling limit has been a long-standing issue of interacting many-body fermion systems. Recently, FeSe semimetal with hole and…
As the simplest iron-based superconductor, FeSe forms a tetragonal structure with transition temperature Tc ~ 8 K. With assistance of pressure, or other techniques, Tc can be greatly enhanced, even to above liquid nitrogen temperature. The…
We report on the emergence of two disconnected superconducting domes in alkali-metal potassium (K)-doped FeSe ultra-thin films grown on graphitized SiC(0001). The superconductivity exhibits hypersensitivity to K dosage in the lower-Tc dome,…
Finding of unconventional superconductivity (USC) in FeSe in an electronic "normal" state with broken $C_{4v}$ rotational symmetry testifies to the diversity of pairing states in Fe-based superconductors. Moreover, such USC emerges as a…
Uncovering the origin of unconventional superconductivity is often plagued by the overwhelming material diversity with varying normal and superconducting (SC) properties. In this article, we deliver a comprehensive study of the SC…
A general feature of unconventional superconductors is the existence of a superconducting dome in the phase diagram as a function of carrier concentration. For the simplest iron-based superconductor FeSe (with transition temperature Tc ~ 8…
FeSe$_{1-x}$Te$_{x}$ superconductors manifest some intriguing electronic properties depending on the value of $x$. In FeSe single crystal, the nematic phase and Dirac band structure have been observed, while topological surface…
Pressure dependence of the electronic and crystal structures of K$_{x}$Fe$_{2-y}$Se$_{2}$, which has pressure-induced two superconducting domes of SC I and SC II, was investigated by x-ray emission spectroscopy and diffraction. X-ray…
Significant manifestation of interplay of superconductivity and charge density wave, spin density wave or magnetism is dome-like variation in superconducting critical temperature (Tc) for cuprate, iron-based and heavy Fermion…
FeSe is a unique high-$T_c$ iron-based superconductor in which nematicity, superconductivity, and magnetism are entangled with each other in the $P$-$T$ phase diagram. We performed $^{77}$Se-nuclear magnetic resonance measurements under…
Here we establish a more complete phase diagram for FeSe system, based on experimental results of nonstoichiometric Fe1-xSe single crystals that we have developed recently, as well as nearly stoichiometric FeSe single crystals. The…
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…