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I will address in my talk two types of hybrid nanostructured systems: 1. Cu2S-Ru hybrid quantum-dots (QDs), comprising a semiconducting Cu2S core encapsulated by a metallic Ru cage-like shell, and 2. Gold nanoparticles chemically linked to a Nb superconducting film. In the first part of my talk I will present our cryogenic scanning tunneling spectroscopy measurements on the Cu2S-Ru hybrids, and on each of their two individual components. The bare Cu2S QDs show reproducible semiconducting-like I-V characteristics with a bandgap of ~1.5 eV. In contrast, the tunneling spectra acquired on the hybrids largely vary with tip position along a single dot, evolving form semiconducting-like characteristics with in-gap states to spectra exhibiting single electron charging effect - the Coulomb blockade and staircase. Surprisingly, periodic negative differential conductance features emerged in the spectra acquired on the empty Ru cages, overtaking the 'conventional' Coulomb staircase. This intriguing phenomenon is well accounted for by the unique multiply-connected cage architecture, which enables a self-gating like effect between neighboring transport channels. Corresponding model and simulations will be presented. In the second part of the talk I will discuss another intriguing effect, where the superconducting critical temperature, TC, of thin Nb films is significantly modified when an ensemble of gold nanoparticles (NPs) are chemically linked it, with a consistent enhancement when using 3 nm long di-silane linker molecules. The TC increases by up to 10% for certain linker length and NPs size. Tunneling spectra acquired on the linked NPs below TC typically exhibit zero-bias peaks. We attribute these results to a pairing mechanism coupling electrons in the Nb and the NPs, mediated by the organic linkers. This coupling may even lead to induced superconducting correlations in the Au nanoparticles. |
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