Superconducting field effect devices with high transition temperature and critical current density

We have investigated buffer layers of Pr/sub 0.55/Y/sub 0.45/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// (PY)BCO for YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO)/SrTiO/sub 3/ field effect devices. The transitions of single unit cell thick YBCO films in (PY)BCO/YBCO/(PY)BCO trilayers depend strongly on the buffer layer thickness, with optimum T/sub c//spl ap/40 K obtained at a buffer layer thickness of 5nm. SuFET devices deposited on such an optimized buffer layer exhibit substantial improvements in channel quality. For a 3.6 nm thick channel, transition temperature >55 K and critical current density /spl sim/10/sup 6/ A/cm/sup 2/ are obtained. The modulations observed in both the normal and superconducting states are consistent with those obtained in earlier work on non-weak-link dominated samples.<
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