Electric-field-induced insulator-metal transition in Pr_(0.5)Ca_(0.5)MnO_(3) thin films in ramp-type junctions

摘要

A large decrease in the electrical resistance of the junction was observed with an applied voltage of several volts in small area ramp-type junctions, YBa_(2)Cu_(3)O_(7-δ)/Pr_(0.5)Ca_(0.5)MnO_(3-z)/SrRuO_(3). The lowest resistivity of the Pr_(0.5)Ca_(0.5)MnO_(3-z) barrier layer attained was ～10~(0) Ω cm, which is much lower than the previously observed resistivities in the electric-field-induced metallic states in a single crystal of Pr_(0.7)Ca_(0.3)MnO_(3) or in stacked junctions with a Pr_(0.5)Ca_(0.5)MnO_(3-z) barrier. The lowest resistivity is still much larger than that of the fully ferromagnetic metallic states induced by a magnetic field. However, it was found that the lowest resistivity is not intrinsic and that it is limited by a series resistance caused by the SrRuO_(3) electrode, including contact resistances. The lower resistivity can be reached using an electrode with a lower resistance.