Spectroscopie des nouveaux états quantiques (INSP-E2), Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, Benoit Douçot, ANR-16-CE30-0011,RODESIS,Supraconductivité dans un seul plan atomique(2016), ANR-14-CE32-0021,MISTRAL,Impuretés magnétiques dans les supraconducteurs: de l'atome au réseau d'impuretés(2014), ANR-15-CE30-0026,SUPERSTRIPES,Etats critiques de supraconducteurs confinés : de phénomènes mésoscopiques à une compréhension microscopique(2015), Brun, Christophe, Supraconductivité dans un seul plan atomique - - RODESIS2016 - ANR-16-CE30-0011 - AAPG2016 - VALID, Appel à projets générique - Impuretés magnétiques dans les supraconducteurs: de l'atome au réseau d'impuretés - - MISTRAL2014 - ANR-14-CE32-0021 - Appel à projets générique - VALID, Etats critiques de supraconducteurs confinés : de phénomènes mésoscopiques à une compréhension microscopique - - SUPERSTRIPES2015 - ANR-15-CE30-0026 - AAPG2015 - VALID
In this habilitation thesis I summarize about 9-10 years of research that I either personally carried out or directed, or to which I actively took part through joint projects with direct colleagues. My topics of research deal with the electronic properties of quantum materials and their nanostructures. This includes mostly superconducting and correlated systems. Through this period of time, I was also interested in several aspects of mesoscopic physics. Using scanning tunneling microscopy (STM) and spectroscopy (STS), we access both the topography of the surface of the material under study and its local electronic energy-resolved properties, at the atomic scale. We thus obtain a real mapping of the local electronic density-of-states (LDOS) of a material for energies close to the Fermi energy, and we observe its evolution as a function of composition, nanostructuring, temperature, or applied magnetic field. In some cases we can also carry out electronic transport measurements in-situ. State-of-the-art experiments are carried out under increasingly extreme conditions combining: ultrahigh vacuum (UHV, 10-11 mbar), very low temperature (down to 300 mK) and strong magnetic field (up to 10 Tesla). These stringent conditions are actually mandatory to study quantum physics using surface sensitive tools, since the LDOS of metallic/superconducting materials is highly dependent of the amount and nature of the impurities present in the material. Our samples are grown in-situ under UHV in a preparation chamber coupled to the microscope, or cleaved in this same chamber for bulk materials. A very strong point of our team is to develop and build our own experimental devices. This allows us to explore the quantum world in experimental conditions that are only beginning to be accessible to commercial devices.