A route from small sized crystals to gated devices using focused ion beams

Current efforts at material discovery divide between exploratory bulk crystal or powder synthesis and targeted growth of key systems in thin film form. Tuning the Fermi level by electrostatic gating is further reserved to a small number of materials available as thin films or millimeter-sized crystals. Here, we present a route to process a smaller single crystal into a gated Hall bar. A micron-sized lamella is cut with a focused ion beam from a crystal protected by a removable coating to minimize surface damage, and transferred into a resin, which is then crosslinked, allowing thin-film like fabrication of electrical contacts for resistivity measurements. Proof-of-concept processing of commercial SrTiO₃ single crystals into ionic liquid gated devices by this method will be presented. The process is expected to enable device fabrication in many emerging material systems available only as small-sized single crystals, such as some heavy fermion compounds.