Our current research is focused on two areas: mesoscopic superconductors and nanomaterials for fast hydrogen gas sensors. We are also exploring intercalated layered materials (for example, graphite, NbSe2...).
One of the great challenges in experimental nanoresearch is to fabricate the desired samples. We have 'in-house' synthesis capacities to produce samples for our own pursuit on science and providing samples to our collaborators. We developed an electrochemical method to grow superconducting lead (Pb) mesocrystals with novel shapes and a vapor deposition approach to fabricate shaped NbSe2 and MgB2 superconducting mesocrystals. NbSe2 and NbN superconducting nanowires and nanoribbons have been achieved by sintering NbSe3 nanostructure precursors in controlled selenium and ammonia atmospheres, respectively. We fabricated superconducting films containing arrays of holes with diameter down to a few nanometers by utilizing nanoporous membranes as substrates. We are working on synthesis of NbSe2 nanocrystals and MgB2 nanowires through solution-based approaches. We also luckily have convenient access to the world-class facilities (field-emission scanning electron microscope, electron-bean lithography and focused ion beam tool) at Argonne National Laboratory.
The physical properties we are pursuing include origins for the matching and commensurate effects observed in superconducting films containing regular arrays of holes. The influence of holes on the anisotropy and the possible existence of metastable vortex states are topics of our recent experiments on porous films. We use magnetic vortices in superconducting mesocrystals as mesoscopic particles to study properties of a few-body system. Superconducting nanowires and nanoribbons provide us unique platforms to pursue few-row vortex physics and Andreev reflection at the nanoscale. We are interested in exploring superconductivity in few-layers system and fluctuation-induced diamagnetism enabled by intercalating layered materials.
We are also exploring potential applications of nanomaterials. Currently, we are concentrated on the development of robust hydrogen gas sensors with short response times and high sensitivities.