A closer inspection of the Meissner transition of bulk Bi2212 by AC susceptibility measurements
Abstract
AC susceptibility measurements show a completed intergranular loss peak in the imaginary part of the susceptibility. This allows thorough investigation of the features observed in the Meissner region. With increasing applied magnetic field, the intergranular peak in χ"(T) shifts to lower temperatures corresponding to the shift of the hump seen at the in-phase trace. We relate this hump to be a projection of the peak in χ". At 800Hz, the two-step structure is evident. But as frequency is increased the intergranular peak becomes narrower and occurs at a higher temperature, consequently the change in slope in χ' becomes smaller. Nevertheless, even at extremely low field range, a projection is still seen in the real part of the susceptibility χ'. Normalization of the data verifies that the projection is quite evident.