The flux pinning properties of the high temperature superconductor YBa2Cu3O7−δ (YBCO) have been conventionally improved by creating both columnar and dot-like pinning centres into the YBCO matrix. To study the effects of differently doped multilayer structures on pinning, several samples consisting of a multiple number of individually BaZrO3 (BZO) and BaCeO3 (BCO) doped YBCO layers were fabricated. In the YBCO matrix, BZO forms columnar and BCO dot-like defects. The multilayer structure improves pinning capability throughout the whole angular range, giving rise to a high critical current density, J
c. However, the BZO doped monolayer reference still has the most isotropic J
c. Even though BZO forms nanorods, in this work the samples with multiple thin layers do not exhibit a c axis peak in the angular dependence of J
c. The angular dependencies and the approximately correct magnitude of J
c were also verified using a molecular dynamics simulation.
We propose a chemical engine in an adiabatic (Thouless) pumping process for a quantum dot connected to external reservoirs under an isothermal condition. Thanks to the geometrical feature in this process, the entropy production is characterized by the geometric metric tensor which is connected to the Fisher information and Hessian of the density matrix in a nonequilibrium steady state. The existence of inequality between the thermodynamic length and entropy production is established. We also establish that the work done on this system characterized by a vector potential is equivalent to the thermodynamic flux. To characterize the chemical engine, we introduce effective efficiency as the relation between the work and entropy production. Through the theoretical analysis of the quantum master equation for the Anderson model of a quantum dot within the wide-band approximation, we illustrate the explicit values of the work, thermodynamic length, and effective efficiency of the engine as functions of the phase difference of the externally controlled chemical potentials.
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