Saw-tooth pattern from flux jumps observed by high resolution M-H curves in MgB2 thin films

Abstract

While flux jumps have been observed in the magnetic hysteresis loops of superconductors, a saw-tooth pattern of the flux jump is known to appear only in a bulk superconductor. But in this study, we were able to observe the saw-tooth pattern in MgB2 thin film with the careful data acquisition method enhancing the data taking capability and report the details of the distribution of the field interval between jumps B-fj, and the size of the flux jump, M-fj. The theory based on Bean's model in the adiabatic approach was adapted and it was compared with experimental results. In addition, we observe the cross-over between the saw-tooth pattern and a rounded saw-tooth pattern, as a byproduct. A patterns diagram of the vortex jump was drawn on the H-T plane. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3457674]