H-T phase diagram for the giant magnetic flux jumps in low temperature superconductors and high temperature superconductors

We have studied magnetothermal instabilities both theoretically and experim entally. Magnetostriction and magnetization hysteresis loops with flux jump s were calculated over a wide range of experimental parameters employing th ree critical state models: the original Bean model, the Kim-Anderson model, and the exponential model. The influence of the magnetic prehistory on the flux jumps, magnetostriction, and the magnetization was investigated for t he LaSrCuO crystal. H - T diagrams of flux instabilities were constructed f rom calculation and from experimental results. One can see good qualitative agreement between these two diagrams. (C) 1998 American Institute of Physi cs.