Novel high-Tc transistors with manganite oxides

One viable approach for transistor-like high-Tc three terminal devices is the quasiparticle injection device (QPID). We have fabricated Au/YBa2Cu3O7/LaAlO3/Nd 0.7Sr0.3MnO3 (NSMO) and Au/YBa 2Cu3O7/LaAlO3/LaNiO3 (LNO) heterostructures on (100) LaAlO3 substrates by pulsed laser deposition for studies of quasiparticle injection effects in high-Tc superconducting thin films. The effect of the injection of spin-polarized quasiparticles from a ferromagnetic NSMO gate was compared to that of unpolarized quasiparticles from a nonmagnetic metallic LNO gate. A current gain greater than nine has been attained for spin-polarized QPIDs, which is an order of magnitude larger than the gain of spin unpolarized QPIDs. Such large effects could be useful in a variety of active high-Tc/colossal magnetoresistance heterostnicture devices. © 1998 American Institute of Physics.