Quantum vortex tunneling in $YBa_2Cu_3O_{7-\delta}$ thin films

TL;DR

This study investigates quantum vortex tunneling in underdoped YBa2Cu3O7−δ thin films by measuring magnetoresistance, revealing a two-dimensional variable range hopping behavior indicative of quantum tunneling effects at low temperatures.

Contribution

It provides experimental evidence of quantum vortex tunneling in cuprate thin films through magnetoresistance measurements and analysis of VRH behavior.

Findings

Magnetoresistance deviates from Arrhenius activation at low T

Data fits 2D VRH model with MR ∝ exp[-(T0/T)^{1/3}]

Vortex tunneling rates influence the VRH temperature scale T0

Abstract

Cuprate films offer a unique opportunity to observe vortex tunneling effects, due to their unusually low superfluid density and short coherence length. Here, we measure the magnetoresistance (\textit{MR}) due to vortex motion of a long meander line of a superconducting film made of underdoped $YBa_2Cu_3O_{7-\delta}$. At low temperatures (\textit{T}), the \textit{MR} shows a significant deviation from Arrhenius activation. The data is consistent with two dimensional Variable Range Hopping (VRH) of single vortices, i.e. $MR\propto exp[-(T_0/T)^{1/3}]$. The VRH temperature scale $T_0$ depends on the vortex tunneling rates between pinning sites. We discuss its magnitude with respect to estimated parameters of the meander thin film.