Room-temperature reduction at SrRuO3–metal interface in hydrogenous atmosphere detected by interface-sensitive resistance measurement

Abstract

Using interface-sensitive resistance measurement techniques, we detected the reducing reaction precursor at the interface between the metallic oxide SrRuO3 and the electrodes under a hydrogenous atmosphere at room temperature. The interface resistance between this polycrystalline oxide and the electrodes (metallic pads or wires) clearly increased with the hydrogen present even at room temperature. In contrast, for bulk SrRuO3, no increase in resistance was found. The rate of increase of the interface resistance depends on the electrode material, for example, that of SrRuO3–Ag is larger than that of SrRuO3–Cu, and the rate is related to the propensity for bulk oxide to reduce; Ag2O is easier to reduce than CuO. The origin of the increase in interface resistance is posited to be the partial deficiency of oxygen in SrRuO3. Our experiments suggest that the reduction at the interface of SrRuO3 occurs at relatively low temperatures (room temperature) compared with the bulk reducing temperature of ≈200°C previously reported. In addition, electrode materials control the reducing reaction at the interface.