We present measurements of the effective surface impedance changes due to a static magnetic field, DZ(H,T)=DR(H,T)+iDZ(H,T), in a Tl-2212 thin film with Tc > 103 K, grown on a CeO2 buffered sapphire substrate. Measurements were performed through a dielectric resonator operating at 47.7 GHz, for temperatures 60 K 6 T < Tc and magnetic fields l0H 6 0.8 T. We observe exceptionally large field induced variations and pronounced super-linear field dependencies in both DR(H) and DX(H) with DX(H)>DR(H) in almost the whole (H,T) range explored. A careful analysis of the data allows for an interpretation of these results as dominated by vortex dynamics. In the intermediate-to-high field range we extract the main vortex parameters by resorting to standard high frequency model and by taking into proper account the creep contribution. The pinning constant shows a marked decrease with the field which can be interpreted in terms of flux lines softening associated to an incipient layer decoupling. Small vortex viscosity, by an order of magnitude lower than in Y-123 are found. Some speculations about these findings are provided.

Pompeo, N., Schneidewind, H., & Silva, E. (2008). Microwave vortex dynamics in Tl-2212 thin films. PHYSICA. C, SUPERCONDUCTIVITY, 468, 852-855 [10.1016/j.physc.2007.11.063].

Microwave vortex dynamics in Tl-2212 thin films

POMPEO, NICOLA;
2008

Abstract

We present measurements of the effective surface impedance changes due to a static magnetic field, DZ(H,T)=DR(H,T)+iDZ(H,T), in a Tl-2212 thin film with Tc > 103 K, grown on a CeO2 buffered sapphire substrate. Measurements were performed through a dielectric resonator operating at 47.7 GHz, for temperatures 60 K 6 T < Tc and magnetic fields l0H 6 0.8 T. We observe exceptionally large field induced variations and pronounced super-linear field dependencies in both DR(H) and DX(H) with DX(H)>DR(H) in almost the whole (H,T) range explored. A careful analysis of the data allows for an interpretation of these results as dominated by vortex dynamics. In the intermediate-to-high field range we extract the main vortex parameters by resorting to standard high frequency model and by taking into proper account the creep contribution. The pinning constant shows a marked decrease with the field which can be interpreted in terms of flux lines softening associated to an incipient layer decoupling. Small vortex viscosity, by an order of magnitude lower than in Y-123 are found. Some speculations about these findings are provided.
Pompeo, N., Schneidewind, H., & Silva, E. (2008). Microwave vortex dynamics in Tl-2212 thin films. PHYSICA. C, SUPERCONDUCTIVITY, 468, 852-855 [10.1016/j.physc.2007.11.063].
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11590/143406
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