title: Interplay Between Optical Bianisotropy and Magnetism in Plasmonic Metamolecules.
abstract: The smallness of natural molecules and atoms with respect to the wavelength of light imposes severe limits on the nature of their optical response. For example, the well-known argument of Landau and Lifshitz and its recent extensions that include chiral molecules show that the electric dipole response dominates over the magneto-electric (bianisotropic) and an even smaller magnetic dipole optical response for all natural materials. Here, we experimentally demonstrate that both these responses can be greatly enhanced in plasmonic nanoclusters. Using atomic force microscopy nanomanipulation technique, we assemble a plasmonic metamolecule that is designed for strong and simultaneous optical magnetic and magneto-electric excitation. Angle-dependent scattering spectroscopy is used to disentangle the two responses and to demonstrate that their constructive/destructive interplay causes strong directional scattering asymmetry. This asymmetry is used to extract both magneto-electric and magnetic dipole responses and to demonstrate their enhancement in comparison to ordinary atomistic materials.
authors.affiliation: Department of Physics and the Center for Complex Quantum Systems, The University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Liuyang
authors.initials: L
authors.lastname: Sun
authors.affiliation: Department of Physics and the Center for Complex Quantum Systems, The University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Tzuhsuan
authors.initials: T
authors.lastname: Ma
authors.affiliation: Department of Physics and the Center for Complex Quantum Systems, The University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Seung-Cheol
authors.initials: SC
authors.lastname: Yang
authors.affiliation: School of Chemical Engineering, Sungkyunkwan University , Suwon 16419, Republic of Korea.
authors.forename: Dong-Kwan
authors.initials: DK
authors.lastname: Kim
authors.affiliation: Korea Basic Science Institute and University of Science and Technology , Daejeon 34113, Republic of Korea.
authors.forename: Gaehang
authors.initials: G
authors.lastname: Lee
authors.affiliation: Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University , Beijing 100875, China.
authors.forename: Jinwei
authors.initials: J
authors.lastname: Shi
authors.affiliation: Department of Physics, University of Texas at El Paso , El Paso, Texas 79968, United States.
authors.forename: Irving
authors.initials: I
authors.lastname: Martinez
authors.affiliation: School of Chemical Engineering, Sungkyunkwan University , Suwon 16419, Republic of Korea.
authors.forename: Gi-Ra
authors.initials: GR
authors.lastname: Yi
authors.affiliation: Department of Physics and the Center for Complex Quantum Systems, The University of Texas at Austin , Austin, Texas 78712, United States.|Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Gennady
authors.initials: G
authors.lastname: Shvets
authors.affiliation: Department of Physics and the Center for Complex Quantum Systems, The University of Texas at Austin , Austin, Texas 78712, United States.|Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Li
keywords: Plasmonics; bianisotropy; meta-molecular; nanoparticle; optical magnetism