We have three current research areas of focus:

Functional Oxides: Complex oxides exhibit a rich range of phenomena, from ferroelectricity, magnetism, charge and orbital ordering, correlated phenomena such as metal-insulator transitions, and intricate coupling of the relevant order parameters.   Our interest is in designing multifunctionality (multiple phenomena coexisting in a single material), and emergent phenomena (where new and unexpected phases beyond ground state are stabilized with strain, fields, and ultrafast light pulses). For more, visit the Functional Oxides page.






Semiconductor Metamaterials:  Our close collaboration with the Badding group (Chemistry, Penn State), has led to the development of High-Pressure confined Chemical Vapor Deposition (HPcCVD) which enables the filling of semiconductor (Si, Ge, ZnSe, metals) inside microstructured silica optical fibers which contain tens to hundreds of extreme aspect ratio holes in a highly periodic array for all-fiber optoelectronics and infrared imaging.  Recently, other nanoscale templates such zeolites, glasses, opals, and even textiles have been infiltrated with high purity semiconductors to create electronic metalattices in the 1-30nm scale that exhibit both quantum confinement and long-range transport. For more, visit the Metamaterials page.

Ge array in silica fiber

Symmetry:  In 2011, Gopalan and Litvin introduced a new antisymmetry operation called rotation reversal symmetry that reverses the sense of any local rigid rotation of a polyhedron in a structure. In 2015, VanLeeuwen and Gopalan generalized this symmetry to distortion-reversal symmetry that applies to all distortions of any set of discrete atoms and even continuous functions such as the electronic wavefunctions. By combining with time reversal symmetry, we have identified 17,803 double antisymmetry groups that have all be explicitly listed by our group. Since distortions are ubiquitous, they apply to a vast range of phenomena from vibrations, structural and electronic phase transitions, diffusion, grain growth, and interface motion. For more, visit the Symmetry page.

Rotation Reversal Symmetry

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