Detailed analysis of magnetic phase diagram in Bi-2223 superconductors

Abstract Magnetic properties of a high-quality Bi-2223 superconducting tape have been studied by various magnetization measurements using SQUID magnetometer for understanding the flux dynamics. The remnant flux relaxation was carried out for a very long time period of up to 24 h. The curve of the magnetization with ln(t) can be divided into two relaxation rates in different periods of time at higher field. A phase transition boundary of temperature and magnetic field, in which the field has two different relaxation rates, is described in a three- to two-dimensional decoupling transition.