Resistance of a perovskite manganite junction limited by series resistance after an electric-field-induced insulator-to-metal transition

摘要

We observed the electric-field-induced insulator-to-metal (IM) transition in YBa_2Cu_3O_(7-δ)/Pr_(1-x)Ca_xMnO_3 (PCMO,x=0.5)/SrRuO_3 ramp-type junctions with a small area of ～6 μm~2 using an external series resistor from 150 Ω to 2 MΩ. As a result, it was revealed that the resistance of the junctions immediately after the transition was on a comparable order to the external series resistance. Therefore, the smaller the external series resistance is, the smaller the resistance of the PCMO film immediately after the IM transition will be. The parasitic resistance in the junction works as a series resistance to the PCMO film. We achieved the minimum resistivity of ～10~(-1) Ω cm by reducing the parasitic resistance in the junctions without an external series resistor. The present results indicate that the intrinsic resistivity, as realized in the magnetic-field- and x-ray-and photon-irradiation-induced IM transitions, can also be achieved in the electric-field-induced IM transition if we succeed in sufficiently diminishing the parasitic resistance.