A series of layered CeO1-xFxFeAs compounds with x=0 to 0.20 are synthesized by the solid state reaction method. Similar LaOFeAs, pure CeOFeAs shows a strong resistivity anomaly near 145 K, which was ascribed spin-density-wave instability. F doping suppresses this instability and leads superconducting ground state. Most surprisingly, transition temperature could reach as high 41 K. Such T_{c} strongly challenges classic BCS theory based on electron-phonon interaction. The closeness phase...

We performed optical spectroscopy measurement on single crystals of ${\mathrm{BaFe}}_{2}{\mathrm{As}}_{2}$ and ${\mathrm{SrFe}}_{2}{\mathrm{As}}_{2}$, the parent compounds FeAs-based superconductors. Both are found to be quite metallic with fairly large plasma frequencies at high temperature. Upon entering spin-density-wave state, formation partial energy gaps was clearly observed surprising presence two different scales. A part Drude component removed by gapping Fermi surfaces. Meanwhile,...

We report on a comprehensive study of the transport, specific heat, magnetic susceptibility, and optical spectroscopy single crystal ${\text{Fe}}_{1.05}\text{Te}$, which undergoes first-order phase transition near 65 K. show that its physical properties are considerably different from other parent compounds FeAs-based systems, presumably attributed to presence excess Fe ions. The charge transport is rather incoherent above transition, no clear signature gap observed below temperature. Strong...

We performed optical spectroscopy measurement on a superconducting Ba0.6K0.4Fe2As2 single crystal with T{c}=37 K. Formation of the energy gaps in far-infrared reflectance spectra below T{c} is clearly observed. A flat and close to unity observed roughly 150 cm;{-1} for T<<T{c}, following an s-wave pairing line shape. more rapid decrease occurs near 200 cm;{-1}, leading peak ratio at T<<T{c} over that T>or=T{c}. determined absolute value penetration depth 10 K as lambda approximately...

We have employed a new route to synthesize single phase F-doped LaOFeAs compound and confirmed the superconductivity above 20 K in this Fe-based system. show that superconductor has rather high upper critical field of over 50 T. A clear signature superconducting gap opening below ${T}_{c}$ was observed far-infrared reflectance spectra, with $2\ensuremath{\Delta}/{\mathrm{kT}}_{c}\ensuremath{\approx}3.5--4.2$. Furthermore, we electron-type conducting carriers low-carrier density.

We have successfully grown high-quality single crystals of ${\text{SrFe}}_{2}{\text{As}}_{2}$ and ${A}_{0.6}{\text{K}}_{0.4}{\text{Fe}}_{2}{\text{As}}_{2}$($A=\text{Sr}$, Ba) using flux method. The resistivity, specific heat, Hall coefficient been measured. For parent compound ${\text{SrFe}}_{2}{\text{As}}_{2}$, an anisotropic resistivity with ${\ensuremath{\rho}}_{c}/{\ensuremath{\rho}}_{ab}$ as large 130 is obtained at low temperatures. A sharp drop in both in-plane out-plane resistivities...

A large and high-quality single crystal (Li0.84Fe0.16)OHFe0.98Se, the optimal superconductor of newly reported (Li1-xFex)OHFe1-ySe system, has been successfully synthesized via a hydrothermal ion-exchange technique. The superconducting transition temperature (Tc) 42 K is determined by magnetic susceptibility electric resistivity measurements, zero-temperature upper critical fields are evaluated as 79 313 Tesla for field along c-axis ab-plane, respectively. ratio out-of-plane to in-plane...

Ir$_{1-x}$Pt$_x$Te$_2$ is an interesting system showing competing phenomenon between structural instability and superconductivity. Due to the large atomic numbers of Ir Te, spin-orbital coupling expected be strong in which may lead nonconventional We grew single crystal samples this investigated their electronic properties. In particular, we performed optical spectroscopic measurements, combination with density function calculations, on undoped compound IrTe$_2$ effort elucidate origin phase...

An organic−inorganic hybrid polymer composed of a Dawson trivanadium-substituted heteropolytungstate ((Bu4N)5[H4P2W15V3O62]) cluster and PS chain are originally designed first synthesized via in situ ATRP. Further characterization includes NMR spectroscopy, FT-IR GPC which proved the purity material. By means cation exchange process, (Bu4N)+-POM-PS was tuned into novel giant amphiphile H+-POM-PS. Immediately, individual molecules self-assembled kinetically favored vesicles DMF. Our work...

We report an in-plane optical spectroscopy study on the iron-selenide superconductor K$_{0.75}$Fe$_{1.75}$Se$_2$. The measurement revealed development of a sharp reflectance edge below T$_c$ at frequency much smaller than superconducting energy gap relatively incoherent electronic background, phenomenon which was not seen in any other Fe-based superconductors so far investigated. Furthermore, feature could be noticeably suppressed and shifted to lower by moderate magnetic field. Our analysis...

Organic polymers have been found widespread commercial applications due to their easy processing and attractive mechanical properties. Concurrently, inorganic polyoxometalates (POMs), a class of metal–oxygen anionic nanosized clusters early transition metals, wide range functions are used in industrial catalysis. In this communication, we report new approach creating the first linear poly(polyoxometalate)s that combine advantages POM clusters. experiment, POM-containing norbornene monomer...

A series of layered nickel-based ${\text{LaNiAsO}}_{1\ensuremath{-}x}{\text{F}}_{x}$ compounds with $x=0--0.15$ are synthesized by solid-state reactions. The pure LaNiAsO exhibits bulk superconductivity ${T}_{c}\ensuremath{\sim}2.75\text{ }\text{K}$. Partial substitution oxygen fluorine increases the transition temperature to $\ensuremath{\sim}3.8\text{ ${\text{LaNiAsO}}_{0.9}{\text{F}}_{0.1}$ sample shows a sharp superconducting and specific-heat jump at critical temperature. magnitude is...

We report the construction of dumbbell-shaped hybrid molecules for programming their hierarchical supramolecular nanostructures through a synergetic self-assembly. Our first molecule is POM-organic-POSS cocluster produced by covalently coupling POM cluster and POSS together an organic tether. Structural analyses demonstrated highly ordered lamellar morphology with 4.9 nm periodicity, indicating strong thermodynamic force driving nanoscale phase separation blocks. The clusters were arranged...

CaCo$_{2}$As$_{2}$, a ThCr$_{2}$Si$_{2}$-structure compound, undergoes an antiferromagnetic transition at \emph{T$_{N}$}=76K with the magnetic moments being aligned parallel to \emph{c} axis. Electronic transport measurement reveals that coupling between conducting carriers and order in CaCo$_{2}$As$_{2}$ is much weaker comparing parent compounds of iron pnictide. Applying field along axis induces two successive spin-flop transitions its state. The magnetization saturation behaviors...

Single-crystalline KFe${}_{2}$As${}_{2}$ and Ca$T$${}_{2}$As${}_{2}$ ($T=\text{Fe}$, Co, Ni, Cu) are synthesized investigated by resistivity, susceptibility, optical spectroscopy. It is found that CaCu${}_{2}$As${}_{2}$ exhibits a similar transition to the lattice abrupt collapse transitions discovered in CaFe${}_{2}$(As${}_{1\ensuremath{-}x}$P${}_{x}$)${}_{2}$ Ca${}_{1\ensuremath{-}x}$$R$${}_{x}$Fe${}_{2}$As${}_{2}$ ($R$ $=$ rare-earth element). The resistivity of approximately follows...

Abstract The originally synthesized hydrophobic hybrid polymer Bu 4 N + ‐POM‐PS is tuned into a giant amphiphile composed of hydrophilic H ‐POM head and PS tail through protonation. Immediately, the amphiphiles self‐assemble vesicles. A further annealing treatment induces an evolution from vesicles to tubular aggregates containing nanotubes wrapped with coronas. After this transformation, grow then arrange in parallel manner form domains. This interesting morphology provides us opportunity...

We report an infrared spectroscopy study on ${\mathrm{K}}_{0.83}$Fe${}_{1.53}$Se${}_{2}$, a semiconducting parent compound of the 245 iron selenide superconductors. The major spectral features are found to be distinctly different from all other Fe-based superconducting systems. Our measurement revealed two peculiar structures: double-peak structure between 4000 and 6000 cm${}^{\ensuremath{-}1}$ abundant phonon modes---much more than expected for 122 structure. elaborate that those could...

We report a systematic study on the effect of partial substitution Sc3+ by Ti4+ in Sr2ScFeAsO3, Ca2ScFeAsO3 and Sr3Sc2Fe2As2O5 their electrical properties. High levels doping result an increased carrier concentration lead to appearance superconductivity with onset Tc up 45 K.

In this study a click chemistry approach was used to synthesize polyoxometalate–polymer hybrids with well-defined structures. The starting materials were two-azido-containing organosilyl derivative of Wells-Dawson-type polyoxometalate and propargyl-terminated poly(ε-caprolactone). clicking reaction between the azido groups alkynyl found be very efficient structures well-defined. This breakthrough will promote great development in synthesis various broaden their potential application.

We report our findings on the macromolecule-to-amphiphile conversion process of a polyoxometalate-polymer hybrid and assembled vesicles formed by aggregation amphiphile. The is composed polyoxometalate (POM) cluster, which covered five tetrabutylammonium (Bu(4)N(+)) countercations, polystyrene (PS) chain. Through cation-exchange Bu(4)N(+) countercations can be replaced protons to form amphiphile hydrophilic, protonated POM cluster hydrophobic PS By implementing directed one-dimensional...

The unique performance of natural materials stems from their hierarchical hybrid structures formed through self-assembly. self-assembly principles have been exploited to create artificial materials. Herein, we demonstrate a bottom-up approach that produces polymer nanocomposites as well self-assembled nanoenhancer for tailoring the properties. is poly(ethylene glycol) (PEG), and aggregates by hybrid. prepared covalent bonding surfactant-encapsulated polyoxometalate (S-POM) complex with PEG...

${\mathrm{Sr}}_{3}{\mathrm{Ir}}_{4}{\mathrm{Sn}}_{13}$ is an interesting compound showing the coexistence of structural phase transition and superconductivity. The at 147 K leads to formation a superlattice. We perform optical spectroscopy measurements across on single-crystal samples ${\mathrm{Sr}}_{3}{\mathrm{Ir}}_{4}{\mathrm{Sn}}_{13}$. study reveals unusual temperature-induced spectral weight transfer over broad energy scale, yielding evidence for presence electron correlation effects....