Laura Sobral Rey- ESR 6, August 2018 - August 2021
University of Konstanz, Germany
Master thesis: "Nanoscale hybrid nanocomposites: NP@ZIF-8"
Combining inorganic nanoparticles (NPs) with nanoscale metal-organic-frameworks (nanoMOFs) would provide hybrid nanomaterials with enhanced properties for technological applications, for instance, in catalysis and drug delivery. Here hybrid nanomaterials with properties derived from metallic NPs and MOFs were produced. The hybrid nanostructures were synthesized by growing ZIF-8 (Zeolitic Imidazolate Framework) around pre-stabilized NPs (Pd and Ag). Our data show that the use of diﬀerent surfactants determine the morphology and size of ZIF-8: the variation of concentration of hexadecyltrimethylammonium bromide (CTAB) leads to diﬀerent sizes; the use of dodecyl sodium sulfate (SDS) make ZIF-8 grow forming planes.
Personal Training Committee
Main supervisor: Elke Scheer, UKON
Co-supervisor: C. Winkelmann, CNRS
Mentor: Pascale Dauguet, Air Liquide Advanced Technologies
At AALTO, Finland (January 2019) to get trained in deposition techniques for very smooth metal layers and defined oxidation
At AL, France (October/November 2019) to run and test the cryogenic CO2 removal system
At CNRS, France (July/August 2021) to get trained in SPM at very low temperature
Competition between Coulomb blockade and multiple Andreev reﬂection
Objectives: The goal of the project is to reveal the nature of particular superconducting charge transport processes, called multiple Andreev reﬂections (MAR) by setting them into competition with Coulomb blockade. Simultaneously I will explore the concept of Coulomb blockade on a microscopic level. Transport in Coulomb blockade-driven systems like single-electron transistors (SETs) requires energy proportional to the square of the charge of the carriers, while the necessary energy for MAR processes decreases with increasing number of carriers. I will use electron beam lithography and shadow evaporation to fabricate aluminum-based SETs comprising one oxide-tunnel junction and one tunable contact using a break-junction. The design will be such that the charging energy will be in the same order as the superconducting energy. MAR contributions will be in situ tuned by the break junction while Coulomb blockade is controlled by a side gate. I will study electron transport at very low temperature in the superconducting S and the normal N states to disentangle contributions originating from Coulomb blockade and from MAR. I will address the question which parameter determines the appearance of Coulomb blockade in the coherent situation, when the island is in the S state (SSS SET) as well, and the non-coherent situation with an N island (SNS-SET). The sample preparation needed to maintain the superconducting state in the junctions while having a normal island will be performed in collaboration with Early Stage Researcher 14 at RAITH (Germany). I will regularly discuss scientific questions and results with Early Stage Researchers 1, 2, 3 (CNRS, France) and 7 (ETH Switzerland), who work on related topics and I will proﬁt from the expertise in mesoscopic superconductivity and Coulomb blockade from CNRS and ETH.