Related papers: Evolution of two-gap behavior of the superconducto…
This paper reports the synthesis and superconducting behaviors of the tetragonal iron-chalcogenide superconductor FeSe. The electrical resistivity and magnetic moment measurements confirmed its superconductivity with a $T_c^{zero}$ and…
In order to investigate details of the superconducting (SC) gap in the iron-chalcogenide superconductors, the specific heat, C, of FeSe_1-x_Te_x_ with x=0.6-1 has been measured in magnetic fields. Using the two-gap model, it has been found…
Superfluid density ($n_s$) in the mixed state of an iron pnictide superconductor Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ is determined by muon spin rotation for a sample with optimal doping ($x=0.4$). The temperature dependence of $n_s$ is…
Iron-chalcogenide superconductor Fe$_{1.03}$Se$_{0.5}$Te$_{0.5}$ has been investigated under high pressure using synchrotron based x-ray diffraction and mid-infrared reflectance measurements at room temperature. Pressure dependence of the…
Identifying the superconducting (SC) gap structure of the iron-based high-temperature superconductors (Fe-HTS's) remains a key issue for the understanding of superconductivity in these materials. In contrast to other unconventional…
We investigate the high-pressure phase of the iron-based superconductor FeSe$_{0.89}$S$_{0.11}$ using transport and tunnel diode oscillator studies. We construct detailed pressure-temperature phase diagrams that indicate that outside of the…
FeSe with the PbO structure is a key member of the family of new high-$T_c$ iron pnictide and chalcogenide superconductors, as while it possesses the basic layered structural motif of edge-sharing distorted FeSe$_4$ tetrahedra, it lacks…
We report the growth and characterization of single crystals of iron chalcogenide superconductor FeCr$_{0.02}$Se. There is an enhancement of the superconducting transition temperature (T$_{\rm c}$) as compared to the T$_{\rm c}$ of the…
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…
The pressure dependence of superconducting transition temperature $T_{\rm c}$ has been investigated through the DC magnetic measurements for FeSe$_{0.8}$ and FeSe$_{1.0}$. For both samples, with increasing pressure $P$, the $T_{\rm…
Single crystal of Lu$_2$Fe$_3$Si$_5$ was studied with the tunnel-diode resonator technique in Meissner and mixed states. Temperature dependence of the superfluid density provides strong evidence for the two-gap superconductivity with almost…
We investigated several FeSe single crystals grown by two different methods by utilizing experimental techniques namely, resistivity, magnetoresistance, specific heat, scanning tunneling microscopy, and spectroscopy. The residual…
Superconducting iron chalcogenide FeSe has the simplest crystal structure among all the Fe-based superconductors. Unlike other iron pnictides, FeSe exhibits no long range magnetic order accompanying the tetragonal-to-orthorhombic structural…
Superconductivity of iron chalocogenides is strongly enhanced under applied pressure yet its underlying pairing mechanism remains elusive. Here, we present a quantum oscillations study up to 45 T in the high-$T_c$ phase of tetragonal…
We describe the approach of the superconducting state as a sequence of cross-over phenomena. As the temperature is decreased, uncorrelated pairing of the electrons leads to the opening of a pseudogap at T_F^*. Upon further lowering the…
We report on high-pressure (p_max = 2.1 GPa) muon spin rotation experiments probing the temperature-dependent magnetic penetration depth in the layered superconductor 2H-NbSe_2. Upon increasing the pressure, we observe a substantial…
Superconductivity arises from two distinct quantum phenomena: electron pairing and long-range phase coherence. In conventional superconductors, the two quantum phenomena generally take place simultaneously, while the electron pairing occurs…
The van-der-Waals gap of iron chalcogenide superconductors can be intercalated with a variety of inorganic and organic compounds that modify the electron doping level of the iron layers. In Lix(C3N2H10)0.37FeSe, a dome in the…
Among iron chalcogenide superconductors, FeS can be viewed as a simple, highly compressed relative of FeSe without nematic phase and with weaker electronic correlations. Under pressure, however, the superconductivity of stoichiometric FeS…
The interplay of orbital and spin degrees of freedom is the fundamental characteristic in numerous condensed matter phenomena, including high temperature superconductivity, quantum spin liquids, and topological semimetals. In iron-based…