Related papers: Interplay between spin density wave and supercondu…
We have performed an isovalent substitution study in a layered titanium oxypnictide system BaTi$_{2}$(Sb$_{1-x}$Bi$_{x}$)$_{2}$O (0$\leq x\leq$ 0.40) by the measurements of x-ray diffraction, electrical resistivity and magnetic…
Using inelastic neutron scattering, we show that the onset of superconductivity in underdoped Ba(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$ coincides with a crossover from well-defined spin waves to overdamped and diffusive spin excitations. This…
Polycrystalline Sr1-xNdxFeAsF samples were prepared at various Nd-doping levels using both a stoichiometric mixture of the starting materials and in slight excess amounts of FeAs. Susceptibility and resistivity of the samples were studied…
There are few inelastic neutron scattering (INS) reports on the superconducting single crystals of FeAs-1111 system, even though it was first discovered in 2008, due to the extreme difficulty in large single crystal growth. In this paper,…
We used high-resolution scanning tunneling spectroscopy to study the hole-doped iron pnictide superconductor Ba$_{0.6}$K$_{0.4}$Fe$_{2}$As$_{2}$ ($T_c=38$ K). Features of a bosonic excitation (mode) are observed in the measured…
AMn6Bi5 materials (A = Na, K, Rb and Cs) consisting of unique Mn-cluster chains emerge as a new family of superconductors with the suppression of their antiferromagnetic (AFM) order under high pressures. Here, we report transverse…
The layered transition metal dichalcogenide compounds 1T-TaS2 and 4H-TaS2 are well known for their exotic properties, which include charge density wave, superconductivity, Mott transition, etc., and lately quantum spin liquid. Here, we…
The doping dependence of spin excitations in Ba(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$ is studied based on a two-orbital model under RPA approximation. The interplay between the spin-density-wave (SDW) and superconductivity (SC) is considered in…
The magnetic properties in the parent compounds are often intimately related to the microscopic mechanism of superconductivity. Here we report the first direct measurements on the electronic structure of a parent compound of the newly…
Since the discovery of superconductivity\cite{1} at 26 K in oxy-pnictide $LaFeAsO_{1-x}F_x$, enormous interests have been stimulated in the fields of condensed matter physics and material sciences. Among the five different structures in…
We report the interplay between charge-density-wave (CDW) and superconductivity of 1$T$-Fe$_{x}$Ta$_{1-x}$S$_{2}$ ($0\leq x \leq 0.05$) single crystals. The CDW order is gradually suppressed by Fe-doping, accompanied by the disappearance of…
Motivated by the premise that superconductivity in iron-based superconductors is unconventional and mediated by spin fluctuations, an intense research effort has been focused on characterizing the spin excitation spectrum in the…
We report the Ni-doping effect on magnetism and superconductivity (SC) in an Eu-containing 112-type system Eu(Fe$_{1-x}$Ni$_{x})$As$_{2}$ ($0\leq x\leq 0.15$) by the measurements of resistivity, magnetization, and specific heat. The undoped…
To clarify superconductivity in EuFe2As2 hidden by antiferromagnetism of Eu2+, we investigated a Ca-substituted sample, Eu0.5Ca0.5Fe2As2, under high pressure. For ambient pressure, the sample exhibits a spin-density-wave (SDW) transition at…
The parent compounds of the recently discovered iron-arsenic (pnictide) high temperature superconductors transition into an intriguing spin density wave (SDW) phase at low temperatures. Progress in understanding this SDW state has been…
We report neutron scattering measurements of cooperative spin excitations in antiferromagnetically ordered BaFe2As2, the parent phase of an iron pnictide superconductor. The data extend up to ~100meV and show that the spin excitation…
We report high-sensitivity microwave measurements of the in-plane penetration depth $\lambda_{ab}$ and quasiparticle scattering rate $1/\tau$ in several single crystals of hole-doped Fe-based superconductor Ba$_{1-x}$K$_x$Fe$_2$As$_2$…
The spin-density wave (SDW) can be considered as a pair of charge density waves (CDWs), one composed only of electrons with up-spins and the other only of electrons with down-spins. The high-temperature superconductivity found in cuprates…
Exploring new unconventional superconductors is of great value for both fundamental research and practical applications. It is a long-term challenge to develop and study more hole-doped superconductors in 1111 system of iron-based…
We present a comprehensive study of the low-temperature heat capacity and thermal expansion of single crystals of the hole-doped Ba1-xKxFe2As2 series (0<x<1) and the end-members RbFe2As2 and CsFe2As2. A large increase of the Sommerfeld…