Similarities in the dynamical behavior across the classical peak effect and the second magnetization peak in single crystals of 2H-NbSe2

The classical peak effect (CPE) and the second magnetization peak (SMP) are two distinct anomalies in critical current of superconductors. A nascent pinned single crystal sample of 2HNbSe2 (Tc (0) ∼7.2 K) shows only the sharp CPE. In a moderately pinned sample (Tc(0) ∼6 K), the sharp CPE broadens with the addition of characteristic structure (stepwise amorphization) between the onset and the peak positions of the CPE. Also, there emerges another anomalous peak akin to SMP prior to the CPE. We have looked at samples of 2H-NbSe2 with intermediate levels of quenched random pinning (Tc(0) ∼ 7.1 K) and successfully explored the two peaks down to 50 mK. (author)