Dimensional Crossover of Vortex Dynamics Induced by Gd Substitution on Bi2212 Single Crystals

TL;DR

This study investigates how Gd substitution in Bi2212 single crystals alters vortex dynamics, revealing a transition from 3D elastic to 2D plastic vortex creep and changes in magnetization behavior.

Contribution

It demonstrates that Gd substitution weakens interlayer coupling and increases anisotropy, causing a dimensional crossover in vortex dynamics.

Findings

Vortex dynamics shift from 3D elastic to 2D plastic with Gd doping.

Second magnetization peak disappears in underdoped samples.

Anisotropy increases due to Gd substitution.

Abstract

The vortex dynamics of Bi$_2$Sr$_2$Ca$_{1-x}$Gd$_x$Cu$_2$O$_{8+\delta}$ single crystals is investigated by magnetic relaxation and hysteresis measurements. By substituting $Ca$ with $Gd$, it is found that the interlayer Josephson coupling is weakened and the anisotropy is increased, which leads to the change of vortex dynamics from 3D elastic to 2D plastic vortex creep. Moreover, the second magnetization peak, which can be observed in samples near the optimal doping, is absent in the strongly underdoped (with 2D vortex) region.