V-I characteristics in the vicinity of order-disorder transition in vortex matter

TL;DR

This paper investigates the V-I characteristics near the order-disorder transition in vortex matter, revealing dynamic coexistence of phases causes the observed resistance peak and frequency-dependent responses.

Contribution

It demonstrates that the peak in differential resistance arises from phase coexistence, challenging the plastic depinning explanation and highlighting dynamic effects in vortex matter.

Findings

r_d peaks near the transition due to phase coexistence

Frequency affects ac and dc responses differently

Opposite behaviors observed with small ac and dc biases

Abstract

The shape of the V-I characteristics leading to a peak in the differential resistance r_d=dV/dI in the vicinity of the order-disorder transition in NbSe2 is investigated. r_d is large when measured by dc current. However, for a small Iac on a dc bias r_d decreases rapidly with frequency, even at a few Hz, and displays a large out-of-phase signal. In contrast, the ac response increases with frequency in the absence of dc bias. These surprisingly opposite phenomena and the peak in r_d are shown to result from a dynamic coexistence of two vortex matter phases rather than from the commonly assumed plastic depinning.