Mesoscale Materials Laboratory explores how symmetry drives the flow of energy in solids, including interaction of light with matter, and how films crystallize from amorphous phase(s).
It is well known how the properties of solids arise from their symmetry, whether this is defined within the bulk interior, or by the presence of a surface or interface. In the Mesoscale Materials Laboratory we study how symmetry-breaking at different length scales alters how light interacts with matter and can challenge conventional notions about the behavior of materials and their properties.
We utilize materials design, modeling, and simulation to control lattice and electronic degrees of freedom and structure, permitting excitation phenomena that can be used to capture, convert, carry and convey energy and information. Epitaxial complex oxide films grown in the Mesoscale Materials Laboratory via physical vapor or atomic layer deposition, offer an exciting palette for exploring emergent structure-properties relationships. We also investigate how such chemically complex thin films evolve and crystallize using solid phase epitaxy. Areas of application of our research include energy conversion, and information and communications technology (ICT).
The MML aims to provide vibrant research training experiences in a multi-disciplinary mentoring environment. Students, postdoctoral staff, and research faculty work in teams to advance understanding of theoretical and experimental limits on physical and functional properties of materials, including their phase stability. The lab team is focused on providing insights into fundamental mechanisms of how light generates currents and voltages, and how light and other waves propagate in solids of particular symmetries. Example phenomena include the bulk photovoltaic effect in ferroelectric insulators; ballistic and shift currents; the collective behavior of electrons in complex oxide two-dimensional electron gases; tunable dielectric response and dielectric loss; and solid-phase epitaxy and atomic layer deposition.
Our facilities include several lab-designed/built growth chambers for pulsed laser deposition of epitaxial complex oxide films, systems for atomic layer deposition and DC and RF sputtering and post-growth processing; capabilities for variable-temperature characterization of carrier transport and impedance from DC to microwave frequencies, scanning probe microscopy, and a laser spectroscopy lab enabling high-resolution Raman scattering, photoluminescence and photocurrent spectroscopies with several magnets, and optical and magneto-optic cryostats permitting study of solids under excitation from the UV to the IR, at temperatures down to 1.5 K, magnetic fields to 7 T, and under different atmospheres.
We also utilize Drexel’s Central Research Facility, which includes X-ray diffractometers, X-ray photoelectron spectroscopy, two transmission and three scanning electron microscopes, one of which is a focused ion beam instrument, and other facilities for sample preparation. We also use the University Research Computing Facility for some of our modeling and simulation work.