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.

Superconducting fluctuation in Bi2Sr2Ca2Cu3Ox

Abstract: Measurements of the resistivity, of the DC Meissner effect, of the isothermal magnetisation, of the specific heat, of the thermal expansion and of the Hall effect are reported for a high quality polycrystalline sample of the 2223 phase of the BiSrCaCuO family of high temperature superconductors. They are discussed in terms of critical fluctuations within ± 10 K about Tc due to a very small coherence volume. Distinct features appear in the data at the Ginzburg-Landau transition temperature (TGL≈107 K) and at the Kosterlitz-Thouless like temperature (T∗KT≈106 K).

Phonon-enhanced superconductivity at the FeSe/SrTiO3 interface

Abstract: The dream of room temperature superconductors has inspired intense research effort to find routes for enhancing the superconducting transition temperature (Tc). Therefore, single-layer FeSe on a SrTiO3 substrate, with its extraordinarily high Tc amongst all interfacial superconductors and iron based superconductors, is particularly interesting, but the mechanism underlying its high Tc has remained mysterious. Here we show through isotope effects that electrons in FeSe couple with the oxygen phonons in the substrate, and the superconductivity is enhanced linearly with the coupling strength atop the intrinsic superconductivity of heavily-electron-doped FeSe. Our observations solve the enigma of FeSe/SrTiO3, and experimentally establish the critical role and unique behavior of electron-phonon forward scattering in a correlated high-Tc superconductor. The effective cooperation between interlayer electron-phonon interactions and correlations suggests a path forward in developing more high-Tc interfacial superconductors, and may shed light on understanding the high Tc of bulk high temperature superconductors with layered structures.

Critical current enhancement by Lorentz force reduction in superconductor–ferromagnet nanocomposites

Abstract: Ferromagnetic pinning centres in superconductors form much deeper potential wells than equivalent insulating or metallic non-superconducting inclusions. However, the resultant pinning forces arising from magnetic inclusions are low because the magnetic interaction takes place over the length scale of the magnetic penetration depth which is large in technological superconductors. Nonetheless, we show that a magnetic inclusion can also reduce the Lorentz force on a vortex, yielding a substantially enhanced critical current density for a given pinning force. We calculate this enhancement for a single vortex pinned by a paramagnetic cylinder as well as a vortex lattice interacting with magnetic inclusions, and find that the inclusion of ferromagnetic particles or rods offers a practical means of enhancing the critical currents in oxide high temperature superconductors.

CaFeAs 2 : A staggered intercalation of quantum spin Hall and high-temperature superconductivity

Abstract: We predict that CaFeAs2, a newly discovered iron-based high-temperature (T-c) superconductor, is a staggered intercalation compound that integrates topological quantum spin Hall (QSH) and superconductivity (SC). CaFeAs2 has a structure with staggered CaAs and FeAs layers. While the FeAs layers are known to be responsible for high T-c superconductivity, we show that with spin orbital coupling each CaAs layer is a Z(2) topologically nontrivial two-dimensional QSH insulator and the bulk is a three-dimensional weak topological insulator. In the superconducting state, the edge states in the CaAs layer are natural one-dimensional topological superconductors. The staggered intercalation of QSH and SC provides us a unique opportunity to realize and explore physics, such as Majorana modes and Majorana fermion chains

Characteristics of mixed phase superconductivity in oxygenated La2CuO4+δ

Abstract: Superoxygenated La 2 CuO 4+δ , produced at 1800 atm and 550°C, has been investigated by the following means; resistivity, Seebeck coefficient Hall coefficient, magneto-resistance, electron microscopy, AC and DC susceptibility, and specific heat. The results are contrasted with those from “reduced” (stoichiometric) La 2 CuO 4 . Unlike the latter Mott insulator, the oxygenated material shows mixed valent, delocalized behaviour. That behaviour is rendered more complex because of phase segregation via spinodal decomposition onsetting just below room temperature. The observed microstructure permits detailed interpretation of the resulting modification in properties. The degree to which the observed superconductivity mirrors that of (La/Sr) 2 CuO 4 is discussed. Restricting the phase segregation by fast cooling inhibits the superconductive behaviour, by promoting lower effective carrier counts and mobilities and greater magnetic admixture. It is shown that phase segregation is not triggered by or coupled to the point at which long-range 3D magnetic order develops within the insulating component of the two-phase mixture. The super-conductivity is presented in terms of the negative- U charge fluctuation model developed earlier.