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.

Superconductivity at 40 K in the Oxygen-Defect Perovskites La2-xSrxCuO4-y

Abstract: Structural, magnetic, and electronic properties of compounds in the series La 2- x Sr x CuO 4- y for 0.05 ≤ x ≤ 1.1, with δ x = 0.025, were studied. Resistance, susceptibility, Meissner, and shielding measurements have revealed superconductivity among several members of the series. For x = 0.15, the transition temperature T c , measured at the midpoint of the resistive transition, is a maximum at 39.3 K with a width of 2 K. At other compositions the transition is broader and occurs at a lower temperature. Annealing the x = 0.15 sample in oxygen at 500°C increases T c to 40.3 K, while annealing at the same temperature under vacuum suppresses the superconductivity. These changes in oxygen content and T c are reversible.

Superconductivity at 90 K in the Tl-Ba-Cu-O system.

Abstract: Stable and reproducible superconductivity has been unambiguously observed in a new Tl-Ba-Cu-O system containing no group-IIIB elements. Resistance in these rare-earth--free oxides starts to drop sharply above 90 K and reaches zero at 81 K. Meissner flux expulsion and diamagnetic shielding show bulk superconductivity. Further substitutions of elements for this system may lead to even higher-temperature superconductors.

Low‐loss substrate for epitaxial growth of high‐temperature superconductor thin films

Abstract: A perovskite‐like single‐crystal substrate material has been investigated that simultaneously permits epitaxial growth of 1‐2‐3 superconductor films and possesses desirable rf properties of low dielectric constant and loss tangent. The lattice constant of 3.792 A provides a lattice match to within 1% of the a axis of 1‐2‐3. Sputtered films of erbium‐barium‐copper‐oxide have been produced on (100) LaAlO3 substrates that exhibit sharp resistive transitions at 90 K (ΔT=1K), bulk superconductivity as determined by ac susceptibility measurements, and nearly single‐crystal growth as evidenced by x‐ray diffraction and high‐resolution scanning electron microscopy. The high‐frequency dielectric properties of LaAlO3 were experimentally investigated at several temperatures. The low‐frequency dielectric constant was measured to be 15 and the microwave loss tangent ranged from 6×10−4 at room temperature to 5×10−6 at 4 K.