Principal Research Scientist, Mechanical Engineering
Massachusetts Institute of Technology
Seminar: Multifunctional Metamaterials
Abstract: Broken inversion and time reversal symmetries affect the electromagnetic wave modes supported by continuous media, which in turn governs thermal radiation and enables control of radiative heat, linear momentum, angular momentum transfer, and nonreciprocal charge transfer. Application of these phenomena can lead to novel methods of thermal management, tunability, clean energy generation, and object manipulation at short length scales. I will discuss our ongoing work on harnessing linear and nonlinear optical phenomena in material systems with broken symmetries, both in the near-field and far-field regimes. First, I will discuss unique features of the near-field heat transfer between two planar surfaces with broken time-reversal symmetry, and the fundamental role played by the surface polariton modes and surface states forming as a result of asymmetric surface conductivity effects. Then, I will present a formalism for Casimir force interactions between multiple nonreciprocal objects, which reveals emergence of lateral Casimir forces due to material nonreciprocity, whose directions are defined by the objects’ mutual orientations. Interestingly, even in thermal equilibrium, these lateral forces may act to relax the system into the minimum energy state without transferring net energy and momentum to the environment. Finally, I will discuss opportunities to engineer nonlinear nonreciprocal responses in ordinary material systems by harnessing the effect of flexoelectricity - a spontaneous bulk material polarization produced by a strain gradient that lifts the material inversion symmetry. We have recently demonstrated nighttime energy generation in a junction-free material with inversion symmetry broken by a strain gradient, and this work may provide a new disruptive technology for carbon-neutral round-the-clock mobile energy generation and in-situ optical energy harvesting with self-powered photodetectors.
About the Speaker: Svetlana Boriskina develops new materials and technologies to harvest and manipulate light and other forms of radiation. Her multi-disciplinary research blends nanophotonics, plasmonics, electronics, thermodynamics and mechanics. Svetlana makes smart fabrics that provide thermal comfort indoors and outdoors and stay clean no matter what, new meta-materials that exhibit color without any dyes or pigments and change it in response to external stimuli, and novel solar harvesting platforms that can provide clean energy and fresh water to off-electrical-grid and disaster-stricken communities. She is the author and co-author of more than 115 peer-reviewed papers, several award-winning courses, and multiple patents. Svetlana is a passionate advocate for science education and science public communication, which she supports via leadership in professional science organizations, conferences and journal editorial boards; mentorship of student groups; and public outreach.
Host: Mona Zebarjadi, associate professor of electrical and computer engineering and materials science and engineering