Electrical transport, magnetic, and structural properties of the vortex lattice of V_3Si in the vicinity of the peak effect

TL;DR

This study investigates the vortex lattice structure and flux dynamics in V_3Si near the peak effect, revealing history-dependent disorder and re-ordering phenomena, supporting the order-disorder transition model.

Contribution

It provides detailed experimental evidence of vortex lattice behavior near the peak effect in V_3Si, including metastability and re-ordering mechanisms, using multiple measurement techniques.

Findings

Vortex lattice structure is well-defined below the peak-effect line.

Metastable disorder occurs below the peak-effect line and can be re-ordered.

Flux flow is observed at the peak-effect line at high currents.

Abstract

The peak effect in critical current density J_c is investigated by studying the flux dynamics in V_3Si using bulk magnetometry, small-angle neutron scattering, and transport measurements on clean single-crystal samples from the same ingot. For a field-cooled history, well-defined structure in the vortex lattice was found for fields and temperatures (H,T) below the peak-effect line H_P(T); above this line, the structure disappeared. History-dependent, metastable disorder is found only for (H,T) below H_P(T) but the vortex system is reproducibly re-ordered either by field-cooling or a low-frequency, pulsed "shaking" transport current. The latter is shown to attain Bardeen-Stephen flux flow. In addition, flux flow is observed at H_P(T) at high current levels. The results, though novel, support the traditional picture of H_P(T) as an order-disorder transition due to the competition between elasticity and pinning.