Onset of decoupling at the melting field of the vortex lattice in Bi2Sr2CaCu2O8 from microwave dissipation

TL;DR

This study investigates microwave dissipation in a Bi2Sr2CaCu2O8 crystal, revealing the onset of vortex lattice decoupling at the melting field and showing that decoupling occurs gradually over a broad magnetic field range.

Contribution

It provides the first microwave dissipation measurements correlated with the vortex lattice melting transition in Bi2Sr2CaCu2O8, highlighting the gradual decoupling process.

Findings

Onset of microwave dissipation matches the vortex lattice melting field.

c-axis resistivity becomes finite at the melting transition.

Decoupling develops gradually over a large magnetic field range.

Abstract

We have measured the microwave dissipation at 10 GHz in a Bi2Sr2CaCu2O8 single crystal, between 75 and 50 K, as a function of the static magnetic field applied parallel to the c axis. We observe a clear-cut onset in the dissipation precisely at the melting field Hm(T), that we identify in the same sample by a step in the static magnetization. We show that this onset can be assigned to the c-axis resistivity becoming finite in our whole temperature range, whereas the in-plane resistivity displays a thermally activated behavior. This suggests that pinning is efficient even at 10 GHz. The normal state dissipation is recovered at field much higher than the melting field, implying that decoupling develops mostly gradually over a large field range.