Controlling, probing, and utilizing strongly-correlated systems
Exotic quantum phenomena, including metal-insulator transition and superconductivity, typically emerge in the so-called “strongly correlated systems” characterized by flat-band dispersions in momentum space, i.e., rather localized wavefunctions in real space. Such systems have been representing a major stream at the frontier of condensed matter physics. We aim to exploit the exquisite control in molecular chemistry to develop the molecule-based strongly correlated system.
Molecules will be assembled on 2D materials to induce (1) possible interfacial hybridizations between the periodically localized molecular states and 2D delocalized band-edge states and (2) periodic dielectric modulations defined by the symmetry and spacing of the molecular patterns; these effects potentially promote the flat-band formation. Additionally, molecular fluorophores with significant charge transfer characters can sensitively detect the surrounding dielectric changes, and thus they can be employed as messengers to deliver the local static and dynamical phase information of strongly correlated systems. In molecule-low-dimensional hybrids, strong correlations, on the other hand, may open new possibilities for realizing multi-electron transfers due to their incompressible nature. We hope these research efforts could build a tunnel connecting molecular/physical chemistry to correlated physics.
Manipulating 2D magnetic phases and spin dynamics
Molecular spin unit
2D substrate with itinerant electrons
Design and control over magnetism down to the 2D limit is crucial for spintronic technologies. However, deliberate control over 2D magnetism has long been a formidable challenge, caused by the spin isotropy. We aim to generically overcome this limitation by establishing artificial 2D magnetic systems with engineered spin anisotropies. This will be achieved via exploiting 2D-supermolecule heterostructures, wherein the spin-spin interactions between supramolecular units are mediated by the itinerant 2D band edge electrons that have spin textures. Such heterostructures combine the degrees of freedom in spin-spin interactions and in functionalities of supermolecules and 2D band structures, thus providing a generic approach to generate artificial 2D magnetic systems with on-demand spin phases controlled by electrical or optical stimuli.
Engineering mixed dimensional materials
Dirac materials, including graphene, single-walled carbon nanotubes, and topological insulators/semimetals display very unique transport properties. We aim to harness this superior feature via engineering mixed dimensional structures with optical control. We will combine semiconducting and metallic Dirac materials having different dimensionalities and exploit binary tunabilities from these materials entities to create designer anisotropic electronic correlations and optical properties. For example, we plan to develop (1) novel 1D interfaces at 1D-2D heterostructures for anisotropic quantum correlations and (2) 2D interfaces at 2D-3D heterostructures for light-driven directional low-energy excitation transport.
General experimental approaches
The research in this laboratory is based on expertise in (1) linear/nonlinear steady-state/ultrafast spectroscopy and microscopy, and (2) microelectronic device sample design and fabrications. Particularly, with the capability of the experimental setup, and the device architectures, we gain experimental controls over the electric field, magnetic field, and temperature. In this regard, we welcome students, postdocs, and scientists from all backgrounds with diverse interests, including, but not limited to, chemistry, condensed matter physics, materials science and engineering, electrical engineering, and photonics & optical engineering to join us!