Evidence for a Two-stage Melting Transition of the Vortex Matter in Bi2Sr2Ca1Cu2O8+d Single Crystals obtained by Muon Spin Rotation

TL;DR

This study provides experimental evidence for a two-stage melting transition in vortex matter within Bi-2212 superconducting crystals, revealing a previously unobserved transition below the irreversibility line through muon spin rotation measurements.

Contribution

It introduces the observation of a second, distinct vortex melting transition below the irreversibility line, supporting a two-stage melting scenario in high-temperature superconductors.

Findings

Evidence for a two-stage vortex melting transition.

Identification of a transition below the irreversibility line.

Support for independent intra-planar and inter-planar vortex melting processes.

Abstract

From muon spin rotation measurements on under- to overdoped Bi-2212 crystals we obtain evidence for a two-stage transition of the vortex matter as a function of temperature. The first transition is well known and related to the irreversibility line (IL). The second one is located below the IL and has not been previously observed. It occurs for all three sets of crystals and is unrelated to the vortex mobility. Our data are consistent with a two-stage melting scenario where the intra-planar melting of the vortex lattice and the inter-planar decoupling of the vortex lines occur independently.