Evidence of a first order like jump in equilibrium magnetization across the peak effect region in superconducting 2H-NbSe$_2$

TL;DR

This study presents magnetization measurements in superconducting 2H-NbSe₂, revealing a first order-like jump in equilibrium magnetization across the peak effect, linked to an order-disorder transition similar to vortex lattice melting.

Contribution

It provides the first evidence of a first order-like transition in equilibrium magnetization across the peak effect in 2H-NbSe₂, connecting it to entropy changes and vortex matter transitions.

Findings

Observation of a first order-like jump in equilibrium magnetization.

Comparison of the jump magnitude to vortex lattice melting in high-Tc superconductors.

Correlation of the magnetization change with entropy variation during the transition.

Abstract

We report magnetization hysteresis measurements in the peak effect region of a very clean single crystal of superconducting 2H-NbSe$_2$ at temperatures very close to T$_c$(0). Through measurement of minor magnetization curves, we infer the equilibrium magnetization curve across the PE region. We observe a small first order like change in equilibrium magnetization across the peak effect. We relate this observation to the entropy change associated with the order-disorder transformation. We further note that the first order like change in the equilibrium magnetization observed in 2H-NbSe$_2$ is comparable to the change(s)observed in the equilibrium magnetization at the FLL melting transition in various high temperature superconductors.