Electric-field-induced switching of resistance [1][2][3][4][5][6][7] has attracted great interest for potential applications in high-performance nonvolatile memory devices known as resistance random access memory (RRAM). [8] Compared to other nonvolatile memory, RRAM has several advantages, such as fast writing times, high densities, and low operating voltages. Switching behavior, as characterized by current-voltage (I-V) data, has been reported in various materials, including metal oxides [1][2][3][4][5][6] and organics. [7] Switching has been observed in both single crystals and polycrystalline materials. According to published studies, switching only occurs in single crystals and epitaxial films when two different types of electrodes are used. On the other hand, switching has been seen in polycrystalline materials, even when the same type of electrode material was used for both electrodes. [2] To date, several models have been proposed to explain this phenomenon: field-induced defects that affect the interface state density, [3] electrons trapped in interface states that change Schottky-like barrier heights, [4] electron injections that change the local atomic structure, [5] and dielectric breakdown that generates filamentary metallic paths. [6,9] However, the essential factors for resistance switching have not yet been identified. Here, we performed high-throughput exploration of electrode materials for an epitaxial thin-film device to determine the appropriate structure and electrode materials required for achieving resistance-switching memory. This work was also helpful for understanding the mechanism of electric-field-induced resistance switching. Fabrication of several types of metal electrodes on an epitaxial Pr 0.7 Ca 0.3 MnO 3 (PCMO) layer and I-V characterization of electrode pairs were carried out by using combinatorial methodology. [10] This methodology ensured a rapid screening of the resistance-switching effect from among many combinations of different materials. Epitaxial PCMO thin films were grown on LaAlO 3 (100) (LAO) single-crystal substrates by pulsed laser deposition (PLD). Coherent growth of the epitaxial PCMO thin film was confirmed by four-circle X-ray diffraction (4cXRD) measurements. Detailed analysis of the 4cXRD pattern revealed that the PCMO thin film was compressively strained on the LAO substrate. Atomic force microscopy (AFM) images showed that the surface of the epitaxial PCMO thin film was atomically flat. Mg, Ag, Al, Ti, Au, Ni, and Pt electrodes with a diameter of 0.2 mm were fabricated on a 10 mm × 10 mm PCMO epitaxial thin film, as shown in Figure 1b. Two-probe I-V characteristics, pulsed-field resistance, and four-probe I-V characteristics were measured for various metal-electrode combinations. Figure 1a shows the I-V characteristics for various combinations of metal electrodes. The applied voltage was swept at a rate of 0.1 V s -1 . The electrode materials are sorted by their work functions.[11] Switching phenomena were clearly observed in pairs of electrodes comprising ...