High-temperature superconductivity

About: High-temperature superconductivity is a research topic. Over the lifetime, 7263 publications have been published within this topic receiving 175377 citations. The topic is also known as: high-temperature superconductivity.

In-situ growth of superconducting NdFeAs(O,F) thin films by Molecular Beam Epitaxy

Abstract: The recently discovered high temperature superconductor F-doped LaFeAsO and related compounds represent a new class of superconductors with the highest transition temperature (Tc) apart from the cuprates. The studies ongoing worldwide are revealing that these Fe-based superconductors are forming a unique class of materials that are interesting from the viewpoint of applications. To exploit the high potential of the Fe-based superconductors for device applications, it is indispensable to establish a process that enables the growth of high quality thin films. Efforts of thin film preparation started soon after the discovery of Fe-based superconductors, but none of the earlier attempts had succeeded in an in-situ growth of a superconducting film of LnFeAs(O,F) (Ln=lanthanide), which exhibits the highest Tc to date among the Fe-based superconductors. Here, we report on the successful growth of NdFeAs(O,F) thin films on GaAs substrates, which showed well-defined superconducting transitions up to 48 K without the need of an ex-situ heat treatment.

Scanning tunneling microscopy and spectroscopy of Bi-Sr-Ca-Cu-O 2:2:1:2 high-temperature superconductors.

Abstract: We have used scanning tunneling microscopy and spectroscopy to investigate the surface-topographic and electronic properties of Bi-Sr-Ca-Cu-O 2:2:1:2 compounds. Even though there are two atoms (Bi and O) per lattice point, only one corrugation maximum per lattice point is observed. Polarity-dependent images show that the corrugations of the images taken at opposite polarities are in phase. We discuss possible explanations for this observation of in-phase corrugations at opposite polarities. Spectroscopic data were obtained at both high and low sample biases. Our data show that the density of surface electronic states near the Fermi level is about 3--4 orders of magnitude smaller than that of a typical metal. These states are only detectable when the stabilization voltage of the tunnel junction is low (1.5 V). The conductivity near zero bias is extremely nonlinear, consistent with a nonmetallic surface layer. Vacuum resonant tunneling studies show that at these low-bias voltages the tip-to-sample distance is very small (\ensuremath{\sim}3--6 \AA{}). This small tip-to-sample distance implies that the conductivity we detect near zero bias might result from the underlying CuO layer. We find evidence of bias-field penetration into the sample, implying that the surface density of states near the Fermi level is too small to screen out the electric field.

Antiferromagnetic fluctuations and d-wave superconductivity in electron-doped high-temperature superconductors

Abstract: We show that, at weak to intermediate coupling, antiferromagnetic fluctuations enhance d-wave pairing correlations until, as one moves closer to half-filling, the antiferromagnetically induced pseudogap begins to suppress the tendency to superconductivity. The accuracy of our approach is gauged by detailed comparisons with quantum Monte Carlo simulations. The negative pressure dependence of ${T}_{c}$ and the existence of photoemission hot spots in electron-doped cuprate superconductors find their natural explanation within this approach.

High-temperature superconductivity. Stripes defeat the Fermi liquid

Abstract: Two studies add further credibility to an emerging picture of electrons in solids known as 'dynamical stripes'. At the same time they challenge the universal validity of the conventional theories of metals and superconductors.