Enhanced Bidimensionality-Driven Ultrahigh Laser-Induced Voltages in High-T-c Superconducting Epitaxial Films

Light/laser-induced voltage (LIV) phenomenon is discovered for decades, which seems quite promising in light/photovoltage-related applications, but actually the LIV improvement is quite limited (several volts level) even after long-term endeavors. To this end, an A-site doubling tailoring strategy is explored in high-T-c superconducting perovskite to endow enhanced structural bidimensionality in terms of decoupling between 2D superconducting planes. High-quality (La1.6-xNd0.4)BaxCuO4 (LNBCO; x = 0.125-0.20) epitaxial films with A-site Ba/Nd doping are fabricated by pulsed laser deposition method. The LNBCO films exhibit ultrahigh laser-induced voltages (LIVs), especially the superior LIVs of higher than 50 V for x = 0.15 and 0.175 and show fast rising time (<85 ns) and long response time (>100 ns). Such a high LIV is several orders/folds larger than that of the existing high-T-c superconductors and other materials reported to date. Systematic influences are investigated in terms of laser irradiation conditions, tilting angle, Seebeck coefficient, etc., suggesting the high LIVs are correlated to charge transport. Simultaneous tailoring over A-site Ba and Nd in LNBCO causes weaken coupling between the CuO2 planes because the La/Ba/Nd-O bonds are elongated and charges are localized within Cu or CuO2 plane. This enables accelerating the charge transport anisotropically, a consequence of enhanced bidimensionality.