Scanning tunneling microscopy and spectroscopy on nickelate thin films

Diplôme Thèse Scanning tunneling microscopy and spectroscopy on nickelate thin films eng 2016-12-05 author Amundsen Thomas 733493 director Renner Christoph 0000-0001-9882-681X 24186 10.13097/archive-ouverte/unige:94798 urn:nbn:ch:unige-947987 Sc. 5049 We present a scanning tunnelling microscopy study of the metal insulator (MI) phase transition in NdNiO3 thin films grown on NdGaO3. Although topographic resolution is limited to grain structures and step edges, we did achieve high resolution and reproducible spectroscopic mapping of the thin film surface. The spectra we measure are either metallic or insulating, and mapping the local gap as a function of position shows the emergence of well-defined insulating domains in a conducting background upon cooling the film through the MI transition. When warming the film through the MI transition, the opposite is observed, with metallic domains appearing in the insulating background. There is no gradual shift in the measured insulating gap amplitude at the phase transition. The measured proportion of metallic surface area as a function of temperature follows the resistive hysteresis loop and allows a direct comparison with a percolation model for the MI phase transition. Scanning tunnelling microscopy Scanning tunneling spectroscopy Metal insulator phase transition Percolation Nickelates Thin films Dewey 500.2 33 Département de physique de la matière quantique 131 false 783 Groupe Renner b7e3c17b-6dae-4b6d-adfc-b8fdd099a455 Thesis Public Amundsen_Thesis2017.pdf 19422159 application/pdf openAccess Faculté des sciences / Section de physique / Département de physique de la matière quantique

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Amundsen, Thomas