Vortex state microwave resistivity in Tl-2212 thin films

TL;DR

This study investigates the microwave resistivity changes in Tl-2212 thin films under magnetic fields, revealing a superlinear field dependence, a crossover in response types, and a scaling property linked to flux line melting.

Contribution

It provides new insights into vortex state microwave resistivity behavior in Tl-2212 thin films, including a novel scaling property and detailed response characteristics.

Findings

Superlinear field dependence of resistivity changes

Crossover from imaginary to real response with temperature/field

Scaling property related to flux line melting

Abstract

We present measurements of the field induced changes in the 47 GHz complex resistivity, $\Delta \tilde \rho(H,T)$, in Tl$_{2}$Ba$_{2}$CaCu$_{2}$O$_{8+x}$ (TBCCO) thin films with $T_{c}\simeq$ 105 K, prepared on CeO$_{2}$ buffered sapphire substrates. At low fields ($\mu_{0}H<$10 mT) a very small irreversible feature is present, suggesting a little role of intergranular phenomena. Above that level $\Delta \tilde \rho(H,T)$ exhibits a superlinear dependence with the field, as opposed to the expected (at high frequencies) quasilinear behaviour. We observe a crossover between predominantly imaginary to predominantly real (dissipative) response with increasing temperature and/or field. In addition, we find the clear scaling property $\Delta \tilde \rho(H,T)=\Delta \tilde \rho[H/H^{*}(T)]$, where the scaling field $H^{*}(T)$ maps closely the melting field measured in single crystals. We discuss our microwave results in terms of loss of flux lines rigidity.