Magnetoresistance Study of c-Axis Oriented YBCO Thin Film

Abstract

The c-axis orientation YBa2Cu3O δ thin film was prepared directly on MgO substrate by the pulse laser deposition. The thickness of the film is 170 nm. The superconducting critical temperature is T c50% = 87.5 K and the width of superconducting transition is ∆T = 1.8 K. The temperature dependences of magnetoresistance were measured up to 90 kOe. The widths of the transition to the superconducting state versus applied magnetic field were derived and they were fitted using the formula: ∆T = CH m + ∆T0. The irreversibility fields as a function of temperature were obtained and fitted by the de Almeida and Thouless-like equation: Hirr = Hirr0(1−T /Tc0) n . The irreversibility field at the liquid nitrogen temperature was calculated and it is Hirr = 43.8 kOe when the applied magnetic field is parallel to the c-axis.

Magnetic Penetration Depth and Coherence Length in a Single‐Crystal YBa2Cu3O7−δ

“…Similar behavior was obtained in works done by other researchers. [ 27,28,38–41 ] This considerable widening of the transition region in high‐temperature superconductors was attributed to the strength of fluctuations in these materials due to high values of T c , weak coherence length ξ , and large anisotropy. [ 42,43 ]…”

“…Similar behavior was obtained in works done by other researchers. [27,28,[38][39][40][41] This considerable widening of the transition region in high-temperature superconductors was attributed to the strength of fluctuations in these materials due to high values of T c , weak coherence length ξ, and large anisotropy. [42,43] These important fluctuations lead to weak pinning in HTSC, unlike the conventional type-II superconductors where pinning is very strong and thus the transition region is sharp.…”