Vortex pinning is dramatically increased in anisotropic High‐Tc superconductors with nanosize inclusions, with relevant consequences for the applications. Special attention has been devoted to the effect of BaZrO3 (BZO) nanoparticles and nanorods on pinning in YBa2Cu3O7‐x (YBCO), due to the interesting interactions of intrinsic (effective‐mass) anisotropy, directionality of nanorods, and elasticity of vortex matter. The interrelation between various sources of anisotropy has stimulated large interest. In this work we compare transport measurements taken in very different dynamic regimes. In particular, we use measurements of the anisotropic transport properties (dc critical current density Jc and 48‐GHz microwave complex resistivity) of driven vortex matter in YBCO with elongated strong‐pinning sites (c‐axis aligned, self‐assembled BZO nanorods, as revealed by TEM investigation) to demonstrate that the effective‐mass angular scaling (anisotropic Ginzburg‐Landau scaling) takes place only in intrinsic physical quantities (flux‐flow resistivity), and not in pinning‐ related Labusch parameter and critical currents. For the intrinsic part (effective‐mass scaling), we get the conventional 3D, function with anisotropy = 5. However, for pinning‐related quantities (Labusch parameter, Jc) a nontrivial angular dependence is isolated. The comparison of the dynamics at different time scales shows evidence for a transition of the vortex matter toward a Mott phase, driven by the presence of nanorods. The strong pinning in dc arises partially from a dynamic effect, and this effect decreases when the magnetic field is tilted away from the alignment with the nanorods.  Interestingly, the dynamic effect survives up to a misalignment of 60o . This work has been partially supported by the Italian FIRB project “SURE:ARTYST” and by EURATOM. N.P. acknowledges support from Regione Lazio.  

Pompeo, N., Augieri, A., Torokhtii, K., Galluzzi, V., Celentano, G., Silva, E. (2013). Directional pinning and anisotropy in YBaCuO with BaZrO nanorods: a comparative microwave and dc study.

Directional pinning and anisotropy in YBaCuO with BaZrO nanorods: a comparative microwave and dc study

POMPEO, NICOLA;TOROKHTII, KOSTIANTYN;
2013-01-01

Abstract

Vortex pinning is dramatically increased in anisotropic High‐Tc superconductors with nanosize inclusions, with relevant consequences for the applications. Special attention has been devoted to the effect of BaZrO3 (BZO) nanoparticles and nanorods on pinning in YBa2Cu3O7‐x (YBCO), due to the interesting interactions of intrinsic (effective‐mass) anisotropy, directionality of nanorods, and elasticity of vortex matter. The interrelation between various sources of anisotropy has stimulated large interest. In this work we compare transport measurements taken in very different dynamic regimes. In particular, we use measurements of the anisotropic transport properties (dc critical current density Jc and 48‐GHz microwave complex resistivity) of driven vortex matter in YBCO with elongated strong‐pinning sites (c‐axis aligned, self‐assembled BZO nanorods, as revealed by TEM investigation) to demonstrate that the effective‐mass angular scaling (anisotropic Ginzburg‐Landau scaling) takes place only in intrinsic physical quantities (flux‐flow resistivity), and not in pinning‐ related Labusch parameter and critical currents. For the intrinsic part (effective‐mass scaling), we get the conventional 3D, function with anisotropy = 5. However, for pinning‐related quantities (Labusch parameter, Jc) a nontrivial angular dependence is isolated. The comparison of the dynamics at different time scales shows evidence for a transition of the vortex matter toward a Mott phase, driven by the presence of nanorods. The strong pinning in dc arises partially from a dynamic effect, and this effect decreases when the magnetic field is tilted away from the alignment with the nanorods.  Interestingly, the dynamic effect survives up to a misalignment of 60o . This work has been partially supported by the Italian FIRB project “SURE:ARTYST” and by EURATOM. N.P. acknowledges support from Regione Lazio.  
Pompeo, N., Augieri, A., Torokhtii, K., Galluzzi, V., Celentano, G., Silva, E. (2013). Directional pinning and anisotropy in YBaCuO with BaZrO nanorods: a comparative microwave and dc study.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11590/174831
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