STSM of Celia González (UAM, Spain) at Forschungszentrum Jülich (Germany)

The aim of this STSM was to advance the fabrication of high-quality van der Waals heterostructures (vdW) for the investigation of the electronic properties of different superconducting materials combining STM and transport measurements. We were particularly interested in new fabrication procedures to prepare devices with atomically clean surfaces, as the one recently developed in Peter Grünberg Institute for Quantum Nanoscience (PGI-3) at Forschungszentrum Jülich.

Standard dry pick-up assembly techniques involve contacting the heterostructure surface with polymers, leaving residues on the surface of the devices. The host laboratory has developed a novel technique for the mechanical assembly of ultra-clean vdW heterostructures called suspended dry pick-up and flip-over which overcomes the drawbacks of existing assembly methods and achieves atomically clean surfaces.

During this time period, Celia learned how to prepare vdW devices using the novel suspended dry pickup and flip-over technique, developed by the host research group. Furthermore, she has fabricated three ultra-clean graphene-based heterostructures for STM studies.

The plan is to measure these devices using STM and compare them to samples fabricated via standard pick-up methods in the home laboratory. If the quality of the samples is sufficient, we will perform electrical transport measurements and attempt the deposition of elements such as hydrogen. We will implement this new fabrication technique in our vdW heterostructures fabrication procedures. This will enable scanning tunnelling microscopy studies of geometries previously only investigated through transport, potentially yielding new insights for material combinations which have not yet been reported in literature.