title: Split-ball resonator as a three-dimensional analogue of planar split-rings.
abstract: Split-ring resonators are basic elements of metamaterials, which can induce a magnetic response in metallic nanosctructures. Tunability of such response up to the visible frequency range is still a challenge. Here we introduce the concept of the split-ball resonator and demonstrate the strong magnetic response in the visible for both gold and silver spherical plasmonic nanoparticles with nanometre scale cuts. We realize this concept experimentally by employing the laser-induced transfer method to produce near-perfect metallic spheres and helium ion beam milling to make cuts with the clean straight sidewalls and nanometre resolution. The magnetic resonance is observed at 600 nm in gold and at 565 nm in silver nanoparticles. This method can be applied to the structuring of arbitrary three-dimensional features on the surface of nanoscale resonators. It provides new ways for engineering hybrid resonant modes and ultra-high near-field enhancement.
authors.affiliation: Data Storage Institute, A*STAR (Agency for Science, Technology and Research), 5 Engineering Drive 1, 117608 Singapore, Singapore.
authors.forename: Arseniy I
authors.initials: AI
authors.lastname: Kuznetsov
authors.affiliation: Nonlinear Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200, Australia.
authors.forename: Andrey E
authors.initials: AE
authors.lastname: Miroshnichenko
authors.affiliation: Data Storage Institute, A*STAR (Agency for Science, Technology and Research), 5 Engineering Drive 1, 117608 Singapore, Singapore.
authors.forename: Yuan Hsing
authors.initials: YH
authors.lastname: Fu
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117583 Singapore, Singapore.
authors.forename: Vignesh
authors.initials: V
authors.lastname: Viswanathan
authors.affiliation: Data Storage Institute, A*STAR (Agency for Science, Technology and Research), 5 Engineering Drive 1, 117608 Singapore, Singapore.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Rahmani
authors.affiliation: 1] Data Storage Institute, A*STAR (Agency for Science, Technology and Research), 5 Engineering Drive 1, 117608 Singapore, Singapore [2] Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117583 Singapore, Singapore.
authors.forename: Vytautas
authors.initials: V
authors.lastname: Valuckas
authors.affiliation: Data Storage Institute, A*STAR (Agency for Science, Technology and Research), 5 Engineering Drive 1, 117608 Singapore, Singapore.
authors.forename: Zhen Ying
authors.initials: ZY
authors.lastname: Pan
authors.affiliation: Nonlinear Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200, Australia.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Kivshar
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117583 Singapore, Singapore.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Pickard
authors.affiliation: Data Storage Institute, A*STAR (Agency for Science, Technology and Research), 5 Engineering Drive 1, 117608 Singapore, Singapore.
authors.forename: Boris
authors.initials: B
authors.lastname: Luk'yanchuk