Search for superconductors with a T c above the liquid nitrogen temperature (77 K) led to the discovery of a high-T c cuprate with a T c above 130 K over two decades ago 16 . Even though the value of T c is only 26 K in the first Fe-based superconductor, LaFeAsO (ref. 17) with the earlier work on superconducting oxides interfaces [3][4][5][6] , demonstrates that interface between two different materials provide not only a rich system for studying two-dimensional (2D) superconductivity, but also a potential pathway to high-T c superconductivity [7][8][9][10][11][12] .Indeed, recent angle-resolved photoemission spectroscopy (ARPES) experiments on the FeSe/STO system revealed different electronic structure from those of bulk FeSe and possible occurrence of superconductivity around 65 K (refs. 13,14). An ex situ transport measurements performed on FeSe/STO protected by multiple layers of FeTe and amorphous Si overlay revealed a zero-resistance T c of 23.5 K and an onset T c > 40 K (ref. 15). Evidently the addition of protection layers suppresses superconductivity in single-layer FeSe. In this work, we report electrical transport measurements on single-layer films of FeSe grown on Nb-doped SrTiO 3 substrate using an in situ 4-point probe (4PP) technique. We found that superconductivity could be obtained even at a temperature as high as 109 K.Single-layer films of FeSe were grown on Nb-doped SrTiO 3 (001) surface by the same method as reported previously 1 , employing extra Se flux in an MBE system equipped with STM/STS and 4PP capabilities. The growth process was monitored by reflection high-energy electron diffraction (RHEED) (Fig. 1a), which allows the precise control of film growth needed to achieve one unit-cell thickness as exactly as possible. The crystal nature of the films was confirmed by STM imaging at both large and atomic scales, as shown in Figs grown on a conducting substrate, it does mean zero resistance of the film as the film shorts the conducting substrate. However, when the 4PP detects a finite voltage, it may not necessarily mean that the sample is not superconducting. Indeed, the 4PP technique is a powerful tool for investigating superconductivity in films that cannot be taken out of a UHV system or an interface that is not accessible by surface probes.Two typical I-V curves collected at 3 K in C1423 and C1234 are shown in Figs. 2b and 2c, respectively. The data demonstrate explicitly that the film is superconducting, with the critical current (I c ) defined by the current value for which the superconducting top layer can no longer short the conducting substrate with a finite resistance. Even though interpretation of the finite voltage in the superconducting I-V curves are complicated, the essentially zero voltage seen at low currents cannot be resulted from artificial effects of the contact, since all four tips of the 4PP have Ohmic contacts with the sample individually (Supplementary Information). It is also interesting to note that the extracted I c have similar values for both measurement con...

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Topological superconductors (TSCs), featuring fully gapped bulk and gapless surface states as well as Majorana fermions, have potential applications in fault-tolerant topological quantum computing. Because TSCs are very rare in nature, an alternative way to study the TSC is to artificially introduce superconductivity into the surface states of a topological insulator through the proximity effect ]. Here we report the experimental realization of the proximity effect-induced TSC in Bi 2 Te 3 thin films grown on a NbSe 2 substrate, as demonstrated by the density of states probed using scanning tunneling spectroscopy. We observed Abrikosov vortices and Andreev lower energy bound states on the surface of the topological insulator, with the superconducting coherence length depending on the film thickness and the magnetic field. These results also indicate that the topological surface states of Bi 2 Te 3 thin films are superconducting and, thus, that the Bi 2 Te 3 =NbSe 2 is an artificial TSC. The feasibility of fabricating a TSC with an individual Majorana fermion bound to a superconducting vortex for topological quantum computing is discussed.

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Amphiphobic, microporous polyurethane (PU) composite microfibrous membranes exhibiting robust waterproof and breathable performances were prepared by the introduction of a novel synthesized fluorinated PU (FPU) containing head perfluoroalkane segment. By employing the FPU incorporation, the pristine PU membranes were endowed with the superhydrophobicity with water contact angle of 156u and the oleophobicity with oil contact angle of 145u. The role of FPU for the tuning of the morphology, surface wettability and mechanical property of resultant membranes were discussed, and a plausible twostep break mechanism upon the external stress is proposed. The quantitative fractal dimension analysis using N 2 adsorption method has confirmed the correlation between the hierarchical roughness and amphiphobicity. Furthermore, the as-prepared membranes exhibited high water resistance (39.3 kPa), good air permeability (8.46 L m 22 s 21 ) and water vapor transmittance (0.384 kg m 22 h 21 ), and comparable tensile strength (10 MPa), suggesting their use as promising materials for a variety of potential applications in protective clothing, bioseparation, membrane distillation, tissue engineering and catalyst carriers, etc., and also provided new insight into the design and development of functional microfibrous membranes through FPU incorporation.