Imaging and Harnessing Percolation at the Metal–Insulator Transition of NdNiO 3 Nanogaps
Résumé
Keywords: metal-insulator transition, phase separation, domain percolation, nanodevice J.H.L. and F.T. contributed equally to this work. Competition between co-existing electronic phases in first-order phase transitions can lead to a sharp change in the resistivity as the material is subjected to small variations in the driving parameter, e.g., the temperature. One example of this phenomenon is the metal-insulator transition (MIT) in perovskite rare-earth nickelates. In such systems, reducing the transport measurement area to dimensions comparable to the domain size of insulating and metallic phases around the MIT should strongly influence the shape of the resistance-temperature curve. Here, we measure the temperature dependence of the local resistance and the nanoscale domain distribution of NdNiO3 areas between Au contacts gapped by 260 down to 40 nm. We find that a sharp resistance drop appears below the bulk MIT temperature at ~105 K, with an amplitude inversely scaling with the nanogap width. By using X-ray photoemission electron microscopy, we directly correlate the resistance drop with the emergence and coalescence of individual metallic domains at the nanogap. Our observation provides a direct insight into percolation at the MIT of rare-earth nickelates.
Domaines
Matière Condensée [cond-mat]
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