Related papers: Unconventional superconductivity induced by suppre…
A new hight Tc Fe-based compound system, AFe2As2 with A = K, Cs, K/Sr and Cs/Sr has been found. Through electron-doping, Tc of the A = K and Cs compounds rises to ~37 K, and finally enter a spin-density-wave state (SDW) through further…
We report on a comparative study of the crystal structure and the magnetic properties of FeSe1-x (x= 0.00 - 0.15) superconducting samples by neutron powder diffraction and magnetization measurements. The samples were synthesized by two…
Transition-metal chalcogenides host various phases of matter, such as charge-density wave (CDW), superconductors, and topological insulators or semimetals. Superconductivity and its competition with CDW in low-dimensional compounds have…
Fermi systems in the crossover regime between weakly coupled Bardeen-Cooper-Schrieffer (BCS) and strongly coupled Bose-Einstein-condensate (BEC) limits are among the most fascinating objects to study the behavior of an assembly of strongly…
From our powder x ray diffraction pattern, electrical transport and magnetic studies we report the effect of isovalent Se substitution at S sites in the newly discovered systems EuSr2Bi2S4F4 and Eu2SrBi2S4F4. We have synthesized two new…
A superconducting transition temperature Tc as high as 100 K was recently discovered in 1 monolayer (1ML) FeSe grown on SrTiO3 (STO). The discovery immediately ignited efforts to identify the mechanism for the dramatically enhanced Tc from…
External pressure driven phase transitions of FeSe are predicted using \textit{ab initio} calculations. The calculations reveal that $\alpha$-FeSe takes transitions to NiAs-type, MnP-type, and CsCl-type FeSe. Transitions from NiAs-type to…
Recent reports of interface-induced superconductivity in the unit-cell films of FeSe on SrTiO3 with a Tc up to ~ 65+-5 K, highest among the Fe-based superconductors and second only to that of the cuprates, have generated great excitement.…
We investigated the pressure effects on the FeSe superconductor and the related compounds. Pressure dependence of superconducting transition temperature (Tc) for FeSe0.8S0.2 exhibits a dome-shaped behavior below 0.76 GPa. On the other hand,…
We propose that the contrasting low-temperature behaviors observed experimentally among isostructural and isoelectronic materials, like non-superconducting and nonmagnetic MgFeGe, magnetically ordered NaFeAs, and superconducting LiFeAs, can…
We have carried out a detailed study to investigate the existence of an insulating parent phase for FeSe superconductor. The insulating Fe4Se5 with specific Fe-vacancy order shows a 3D-Mott variable range hopping behavior with a Verwey-like…
Recently discovered A-Fe-Se (A - alkali metal) materials have questioned the most popular theories of iron-based superconductors because of their unusual electronic structure [1]. Controversial photoemission data taken in the…
We present a novel method for embedding spin and charge fluctuations in an anisotropic, multi-band and full-bandwidth Eliashberg treatment of superconductivity. Our analytical framework, based on the random phase approximation, allows for a…
This paper reports that ~10-nm-thick FeSe thin films exhibit insulator-like behavior in terms of the temperature dependence of their electrical resistivity even though bulk FeSe has a metallic electronic structure that has been confirmed by…
FeSe is a unique member of the family of iron-based superconductors, not only because of the high values of $T_{c}$ in FeSe monolayer, but also because in bulk FeSe superconductivity emerges inside a nematic phase without competing with…
We have synthesized polycrystalline samples and single crystals of Fe(Te1-xSx)y, and characterized their properties. Our results show that the solid solution of S in this system is limited, < 30%. We observed superconductivity at ~ 9 K in…
The evolution of the superconducting transition temperature ($T_c$) in FeSe was investigated under in-plane, out-of-plane, and hydrostatic compression. For pressures up to 0.6 GPa, $T_c$ increases regardless of the compression mode,…
We have carried out detailed magnetic and transport studies of the new Sr0.5Ce0.5FBiS2-xSex (x = 0.5, 1) superconductors derived by doping Se in Sr0.5Ce0.5FBiS2. Se-doping produces several effects: it suppresses semiconducting like behavior…
We report our study of the evolution of superconductivity and the phase diagram of the ternary Fe(Se1-xTex)0.82 (0<=x<=1.0) system. We discovered a new superconducting phase with Tc,max = 14 K in the 0.3 < x < 1.0 range. This…
Recently, the superconductors' community has witnessed an unsettled debate regarding whether iron-based superconductors, in particular FeSe and FeSe$_{1-x}$S$_x$, are in the Bardeen-Cooper-Shrieffer (BCS) - Bose-Einstein condensation (BEC)…