A NOVEL TECHNIQUE TO MEASURE MAGNETIZATION HYSTERESIS CURVES IN THE PEAK-EFFECT REGIME OF SUPERCONDUCTORS

Magnetisation hysteresis of type II superconductors measured using SQU ID-based Magnetic Property Measurement System (MPMS) made by Quantum D esign is known to be affected by inhomogeneity in the external field. We present a new method, viz., half-scan technique, for measuring magn etisation hysteresis loops using MPMS, This technique circumvents the problems caused by field inhomogeneity. We have used this technique to measure magnetisation hysteresis loops in the peak-effect regime of s uperconducting CeRu2 and 2H-NbSe2. The magnetisation hysteresis obtain ed using half-scan technique is found to be significantly larger than that obtained by conventional MPMS measurements. At very low fields wh ere the extent of field inhomogeneity is not significant and in the re versible region, the results of the half-scan technique are comparable to those obtained using conventional technique. Moreover, hysteresis measurements are shown to be independent of scan length used in thr me asurement, thus reaffirming that the results are unaffected by the fie ld inhomogeneity. (C) 1998 Elsevier Science B.V.