*ITAMP Lunch Seminar* *Speaker: *Thomas Christensen (MIT) *Date:* Thursday, April 19th *Time:* 12:00-1:00 pm Includes Pizza. *Title: Non-conventional surface and edge effects in plasmonics* *Abstract: *I will discuss some recent work, which exemplify aspects of plasmonics that broadly fall under the category of non-conventional electronic and optical interface effects. Quantum corrections in nanoplasmonics [1] exemplifies the former aspect; for structural feature-sizes or resonant wavelengths approaching the few-nanometer regime, the conventional, local description of electromagnetics breaks down due to its omission of electronic spill-out, surface-enabled Landau damping, and nonlocality. In noble metals, a hydrodynamic model provides a decent effective remedy to the conventional approach, e.g. reproducing experimentally measured blueshifts and regularizing several singular limits of the conventional approach. Though popular and physically transparent, however, the hydrodynamic model is not a generic remedy due to its neglect of spill-out and surface-enabled Landau damping. I will discuss how a recently developed framework, based on the so-called Feibelman *d*-parameters, allows an general, analytical, and straightforward account of all surface-related corrections with TDDFT-level accuracy. Finally, I will discuss our recent work on the prediction of high-frequency topological plasmonic edge modes in structured graphene under a magnetic bias [2] as well as the experimental measurement of low-frequency topological magnetoplasmonic edge modes in the 2D electron gas of a hetero-junction. [1] T. Christensen, W. Yan, A.-P. Jauho, M. Soljačić, & N.A. Mortensen, *Quantum corrections in nanoplasmonics: shape, scale, and material*, Phys. Rev. Lett. *118*, 157402 (2017) [2] D. Jin*, T. Christensen*, M. Soljačić, N.X. Fang, L. Lu, & X. Zhang, *Infrared topological plasmons in graphene*, Phys. Rev. Lett.118, 245301 (2017) *Location: *B-106 @ Center for Astrophysics (60 Garden Street) *Directions: *After entering the lobby of the CfA, turn right to enter the hallway of the B building. In the hallway, turn right again, B-106 will be at the end of the hallway on the left side.