Retaining a dissipation-free state while carrying large electrical currents is a challenge that needs to be solved to enable commercial applications of high-temperature superconductivity. Here, we show that the controlled combination of two effective pinning centres (randomly distributed nanoparticles and self-assembled columnar defects) is possible and effective. By simply changing the temperature or growth rate during pulsed-laser deposition of BaZrO(3)-doped YBa(2)Cu(3)O(7) films, we can vary the ratio of these defects, tuning the field and angular critical-current (Ic) performance to maximize Ic. We show that the defects' microstructure is governed by the growth kinetics and that the best results are obtained with a mixture of splayed columnar defects and random nanoparticles. The very high Ic arises from a complex vortex pinning landscape where columnar defects provide large pinning energy, while splay and nanoparticles inhibit flux creep. This knowledge is used to produce thick films with remarkable Ic(H) and nearly isotropic angle dependence.
Epitaxial c-axis oriented BiFeO3 (BFO) thin films were deposited on (001) Nb-doped SrTiO3 (Nb-STO) substrates by pulsed laser deposition. Introducing Bi vacancies caused the BFO thin film to evolve to a p-type semiconductor and formed a p-n heterojunction with an n-type semiconductor Nb-STO. The current density versus voltage (J-V) and capacitance versus voltage (C-V) characteristics of the heterojunction were investigated. A typical rectifying J-V effect was observed with a large rectifying ratio of 5×104. Reverse C-V characteristics exhibited a linear 1∕C2 versus V plot, from which a built-in potential of 0.6V was deduced. The results show a potential application of BFO/Nb-STO heterojunction for oxide electronics.
Epitaxial c-axis oriented BiFeO3 (BFO) thin films were deposited on conductive SrRuO3 (SRO) on (001) SrTiO3 substrates by pulsed laser deposition. A Pt/BFO/SRO capacitor was constructed by depositing a top Pt electrode. The leakage current density versus. electric field characteristics were investigated from 80to350K. It was found that the leakage mechanisms were a strong function of temperature and voltage polarity. At temperatures between 80 and 150K, space-charge-limited current was the dominant leakage mechanism for both negative and positive biases. On the other hand, at temperatures between 200 and 350K the dominant leakage mechanisms were Poole-Frenkle emission and Fowler-Nordheim tunneling for negative and positive biases, respectively.
Antiperovskite Li3OCl superionic conductor films are prepared via pulsed laser deposition using a composite target. A significantly enhanced ionic conductivity of 2.0 × 10−4 S cm−1 at room temperature is achieved, and this value is more than two orders of magnitude higher than that of its bulk counterpart. The applicability of Li3OCl as a solid electrolyte for Li‐ion batteries is demonstrated.
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