Related papers: Tracing magnetism and pairing in FeTe-based system…
Iron-based superconductors (FBS) comprise several families of compounds having the same atomic building blocks for superconductivity, but large discrepancies among their physical properties. A longstanding goal in the field has been to…
High-pressure magnetization, structural and 57Fe M\"ossbauer studies were performed on superconducting Rb0.8Fe1.6Se2.0 with Tc = 32.4 K. The superconducting transition temperature gradually decreases on increasing pressure up to 5.0 GPa…
This article reviews recent experimental investigations on two binary Fe-chalcogenides: FeSe and Fe$_{1+y}$Te. The main focus is on synthesis, single crystal growth, chemical composition, as well as on the effect of excess iron on…
We propose a non-BCS mechanism for superconductivity in hole-underdoped cuprates based on a gauge approach to the {\it t-J} model. The gluing force is an attraction between spin vortices centered on the empty sites of two opposite N\'eel…
The superconducting properties of a recently discovered high $T_{\rm c}$ superconductor, Sr/ammonia-intercalated FeSe, have been measured using pulsed magnetic fields down to $4.\,\rm {K}$ and muon spin spectroscopy down to $1.5\,\rm K$.…
The transport and structural properties of Fe1+yTe1-xSx (x=0, 0.05, and 0.10) crystals were studied in pulsed magnetic fields up to 65 T. The application of high magnetic fields results in positive magnetoresistance effect with prominent…
The iron chalcogenide Fe1+y(Te1-xSex) is structurally the simplest of the Fe-based superconductors. Although the Fermi surface is similar to iron pnictides, the parent compound Fe1+yTe exhibits antiferromagnetic order with in-plane magnetic…
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…
Fe-based superconductors exhibit a diverse interplay between charge, orbital, and magnetic ordering1-4. Variations in atomic geometry affect electron hopping between Fe atoms5,6 and the Fermi surface topology, influencing magnetic…
In order to gain a deep insight into $f$-electron properties of filled skutterudite compounds from a microscopic viewpoint, we investigate the multiorbital Anderson model including Coulomb interactions, spin-orbit coupling, and crystalline…
Structural investigations by means of transmission electron microscopy (TEM) on KFexSe2 with 1.5 \leq x \leq 1.8 have revealed a rich variety of microstructure phenomena, the KFe1.5Se2 crystal often shows a superstructure modulation along…
When superconductivity couples with noncollinear spin textures, rich physics arises; for instance, singlet Cooper pairs can be converted to triplet pairs, and topological superconductors can be realized. For their applications, the…
The formation of Cooper pairs, a bound state of two electrons of opposite spin and momenta by exchange of a phonon [1], is a defining feature of conventional superconductivity. In the cuprate high temperature superconductors, even though it…
Odd-parity magnetism constitutes an intriguing phase of matter which breaks inversion symmetry while preserving time-reversal symmetry. Here we demonstrate that the Fe-based superconductors exhibiting coplanar magnetic order realize an…
In this article we review essential natures of superconductivity in strongly correlated electron systems (SCES) from a universal point of view. After summarizing experimental results on typical materials such as high-$T_{\rm c}$ cuprates,…
Since 2008, many new families of iron-based high temperature (high-$T_c$) superconductors have been discovered \cite{Hosono,ChenXH,FeTe,ChenXL}. Unlike all parent compounds of cuprates that share a common antiferromagnetically (AF) ordered…
Transverse-field muon-spin rotation measurements performed on two samples of LiFeAs demonstrate that the superfluid stiffness of the superconducting condensate in relation to its superconducting transition temperature is enhanced compared…
We have studied local magnetic moment and electronic phase separation in superconducting K$_{x}$Fe$_{2-y}$Se$_2$ by x-ray emission and absorption spectroscopy. Detailed temperature dependent measurements at the Fe K-edge have revealed…
The phenomenon of oxygen incorporation induced superconductivity in iron telluride (Fe1+yTe, with antiferromagnetic (AFM) orders) is intriguing and quite different from the case of FeSe. Until now, the microscopic origin of the induced…
Iron chalcogenide superconductors are multi-band systems with strong electron correlations. Here we use angle-resolved photoemission spectroscopy to study band dependent correlation effects in single-layer FeSe/Nb:BaTiO3/KTaO3, a new iron…