organic superconductors have π-molecular orbitals, from which electrons can become delocalized, giving rise to metallic conductivity due to orbital overlap between adjacent molecules. Here we report the discovery of superconductivity at a transition temperature (T c ) of ~5 K in alkali-metal-doped phenanthrene. A 1-GPa pressure leads to a 20% increase of T c , suggesting that alkali-metal-doped phenanthrene shows unconventional superconductivity. Raman spectra indicate that alkali-metal doping injects charge into the system to realize the superconductivity. The discovery of superconductivity in A 3 phenanthrene (where A can be either K or Rb) produces a novel broad class of superconductors consisting of fused hydrocarbon benzene rings with π-electron networks. An increase of T c with increasing number of benzene rings from three to five suggests that organic hydrocarbons with long chains of benzene rings are potential superconductors with high T c .

We report the evolution of superconductivity in an FeSe thin flake with systematically regulated carrier concentrations by the liquid-gating technique. With electron doping tuned by the gate voltage, high-temperature superconductivity with an onset at 48 K can be achieved in an FeSe thin flake with T_{c} less than 10 K. This is the first time such high temperature superconductivity in FeSe is achieved without either an epitaxial interface or external pressure, and it definitely proves that the simple electron-doping process is able to induce high-temperature superconductivity with T_{c}^{onset} as high as 48 K in bulk FeSe. Intriguingly, our data also indicate that the superconductivity is suddenly changed from a low-T_{c} phase to a high-T_{c} phase with a Lifshitz transition at a certain carrier concentration. These results help to build a unified picture to understand the high-temperature superconductivity among all FeSe-derived superconductors and shed light on the further pursuit of a higher T_{c} in these materials.

We successfully grew the high-quality single crystal of Rb0.78Fe2Se1.78, which shows sharp superconducting transition in magnetic susceptibility and electrical resistivity. Resistivity measurements show the onset superconducting transition (Tc) at 32.1 K and zero resistivity at 30 K. From the low-temperature iso-magnetic-field magnetoresistance, large upper critical field Hc2(0) has been estimated as high as 180 T for in-plane field and 59 T for out-of-plane field. The anisotropy H ab c2 (0)/H c c2 (0) is around 3.0, right lying between those observed in KxFe2Se2 and CsxFe2Se2.

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Y-TZP all-ceramic restoration veneered by fully anatomical technique was the most transparent and lightest, while restorations veneered by cutback technique were the least translucent and the darkest.

Unconventional superconductivity from heavy fermion (HF) is always observed in f-electron systems, in which Kondo physics between localized f-electrons and itinerant electrons plays an essential role. Whether HF superconductivity could be achieved in other systems without f electrons, especially for d-electron systems, is still elusive. Here, we experimentally study the origin of d-electron HF behavior in iron-based superconductors (FeSCs) AFe 2 As 2 (A = K, Rb, Cs). Nuclear magnetic resonance on 75 As reveals a universal coherent-incoherent crossover with a characteristic temperature T*. Below T*, a so-called "Knight shift anomaly" is first observed in FeSCs, which exhibits a scaling behavior similar to f-electron HF materials. Furthermore, the scaling rule also regulates the manifestation of magnetic fluctuation. These results undoubtedly support an emergent Kondo scenario for the d-electron HF behavior, which suggests the AFe 2 As 2 (A = K, Rb, Cs) as the first material realization of d-electron HF superconductors.Superconductivity in heavy fermion (HF) materials is a conundrum in condensed matter physics. Conventional phonon-mediated pairing mechanism is failed in this case, suggesting an unconventional pairing mechanism similar to that in cuprates and organic superconductors (1). So far, only HF materials containing f electrons could be the hosts for unconventional superconductivity. Whether unconventional superconductivity could be achieved in HF materials without f electrons is still unknown. In f-electron HF materials, Kondo lattice has been widely accepted as the starting point for discussing the underlying physics (2). In two-fluid model of Kondo lattice (3, 4, 5), coherent state emerges below a characteristic temperature T* as the localized f-electrons collectively reduce their entropy by hybridizing with the itinerant electrons to form a new state of matter, an itinerant heavy-electron Kondo liquid (KL) that displays scaling behavior. The emergent KL coexists with the hybridized spin liquid that describes the lattice of local moments whose magnitude has been reduced by hybridization. "Hybridization effectiveness" has been proposed as the organizing principle responsible for the emergence of low-temperature order in HF systems, including unconventional superconductivity (5). Although Kondo picture for HF has achieved a great success in f-electron materials, the fate of Kondo picture in HF materials without f electrons, especially for d-electron systems, is still controversial. Besides Kondo scenario (6), many alternative scenarios, such as lightly doped Mott insulator (7), geometrical frustration via antiferromagnetic interactions (8) and spin-orbital fluctuations (9), have been proposed to responsible for HF behavior in d-electron systems. In addition, searching for unconventional superconductivity in the existing d-electron HF materials is still not successful.Recently, a remarkable mass enhancement was observed in heavily hole-doped Fe-based superconductors (FeSCs) AFe 2 As 2 (A = K, Rb, Cs). As sh...