Year: 1993
Type: article
Abstract: Measurements of voltage-current (V-I) characteristics and critical currents of 2212 and 2223 Ag-clad Bi-Sr-Ca-Cu-O tapes at 0<B<7 T and 4.2 and 77 K are presented. We show that the V-I curves are nonlinear at I<Ic and become linear above the critical current I≳Ic due to the effect of the Ag cladding. It is shown that the V-I curves can be well described by a simple universal formula, which enables one to extract Ic(T, B) and the flux creep rate s(T, B) from the resistive measurements, taking into account the effects of voltage criterion, strong nonlinearity of V(I) and I<Ic and the dependence of the resistivity of Ag upon T and B. For a 2212 tape, Ic(B) is shown to decrease as B−α with α=0.15 at 4.2 K, and exponentially at 77 K. For a 2223 tape, Ic(B) displays a power law dependence with α=0.1–0.3 at 4.2 K, whereas at 77 K Ic(B) can be well described by the formula I0b−1/2(1−b), where b=B/B*, and B* is the irreversibility field. The results are interpreted in terms of strong bulk pinning modified by thermal fluctuations.
Source: Applied Physics Letters
DOI: 10.1063/1.109577
Institution: University of Wisconsin–Madison
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2062015019