NONLOGARITHMIC MAGNETIC-RELAXATION IN A HIGHLY ORIENTED BI-BASED SUPERCONDUCTING TAPE

Abstract

Magnetic Relexation was studied at a wide range of temperatures and magnetic fields for a Ag-sheathed Bi-based superconducting tape with highly-c-axis orientation and high critical current density (J(c) > 10(4) A/cm2 at 77 K and 0 T). Under certain conditions, it is found that the magnetization data varies nonlinearly with ln(t) for entire period of time (t > 10(4) s). The curves can be divided into two relaxation rate (dM/dln(t)) in different period of time. It was observed that the lower the temperature is, the higher the magnetic field needs to bend a logarithmic line into a curve with two different relaxation rate (dM/dln(t)) in different region of time. The diagram of temperature and magnetic field was obtained from the experiment.