Hysteresis Effects in Magnetovoltage Measurements in Superconducting

• Published in: IEEE transactions on applied superconductivity Vol. 19; no. 3; pp. 2744 - 2747
• Main Authors: Olutas, M., Yetis, H., Altinkok, A., Kilic, A., Kilic, K.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2009; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Current measurement; Flux pinning; High temperature superconductors; Magnetic field measurement; Magnetic flux; Magnetic hysteresis; magnetovoltage; Powders; Shape measurement; Superconducting magnets; Superconductivity; type-II superconductors
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2009.2017878

Hysteresis effects in superconducting MgB 2 have been studied systematically by magnetovoltage measurements (V-H curves) as a function of transport current ( I ), temperature (T) and sweep rate of external magnetic field ( H ), (dH/dt). It was observed that time dependent effects appear as the field sweep rate (dH/dt) varies. This reflects itself as a decrease in the width of V-H loops with decreasing of dH/dt. The dissipation measured in V-H curves does not change as the sweep rate of external magnetic field is varied. It was observed that the measured dissipation in V-H curves is independent of field orientation of H with respect to I . Furthermore, it was observed that there is a significant asymmetry in V-H loops between forward and reverse regions. The physical observations were interpreted mainly in terms of flux de-trapping/trapping and thus the difference in the local fields trapping in the grains between increasing and decreasing branches.