Evolution in the split-peak structure across the Peak Effect region in   single crystals of $2H$-NbSe$_2$
  We have explored the presence of a two-peak feature spanning the peak effect (PE) region in the ac susceptibility data and the magnetization hysteresis measurements over a wide field-temperature regime in few weakly pinned single crystals of $2H$-NbSe$_2$, which display reentrant characteristic in the PE curve near $T_c$(0). We believe that the two-peak feature evolves into distinct second magnetization peak anomaly well separated from the PE with gradual enhancement in the quenched random pinning. 
A. D. Thakur, T. V. Chandrasekhar Rao, S. Uji, T. Terashima, M. J.   Higgins, S. Ramakrishnan and A. K. Grover