Doping Dependence of Vortex Regimes in Y$_{1-x}$Pr$_{x}$Ba$_{2}$Cu$_{3}$O$_{7-\delta}$ Single Crystals

TL;DR

This study investigates how doping levels affect vortex behavior in YPrBaCuO superconductors, revealing non-monotonic changes in vortex regimes and the coexistence of creep mechanisms influenced by charge carrier density.

Contribution

It provides new insights into the doping dependence of vortex regimes and creep mechanisms in YPrBaCuO superconductors, highlighting the role of charge carrier density.

Findings

Maximum SMP at x=0.34 doping level

Different temperature dependences of H_on and H_sp

Coexistence of elastic and plastic creep above H_on

Abstract

Magnetic relaxation measurements on a series of Y$_{1-x}$Pr$_{x}$Ba$_{2}$Cu$_{3}$O$_{7-\delta}$ ($x = 0.13, 0.34, 0.47$) single crystals were performed over a large field and temperature range in order to investigate the characteristics of the vortex matter across the second magnetization peak (SMP). The magnitude of the SMP varies non-monotonically with the Pr concentration; i.e., the irreversible magnetization normalized by its value at the onset field $H_{on}$ displays a maximum for the $x = 0.34$ single crystal. The two characteristic fields, $H_{on}$ and $H_{sp}$, follow different temperature $T$ dependences: $H_{on} \propto T^{\nu_{on}}$ and $H_{sp} \propto [1-(T/T_{c})^{2}]^{\nu_{sp}}$. The extracted values of the apparent activation energy $U^\ast$ and the creep exponent $\mu$ display a maximum at a field $H_{on} < H^\ast < H_{sp}$. Their field dependences point toward the coexistence of both elastic and plastic creep for $H > H_{on}$. The degree of participation of each creep mechanism is determined by the charge carrier density, which controls both the elastic properties of the vortex matter and the pinning potential.