Exploring metastability via the third harmonic measurements in single   crystals of $2H$-$NbSe_2$ showing anomalous Peak effect
  We explore the metastability effects across the order-disorder transition pertaining to the peak effect phenomenonon in critical current density ($J_c$) via the first and the third harmonic ac susceptibility measurements in the weakly pinned single crystals of $2H$-$NbSe_2$. An analysis of our data suggests that an imprint of the limiting (spinodal) temperature above which $J_c$ is path independent can be conveniently located in the third harmonic data ($\chi_{3\omega}^{\prime}$). 
A. D. Thakur, S. S. Banerjee, M. J. Higgins, S. Ramakrishnan, A. K.   Grover