Magnetism in one-dimensional metamaterials: Double hyperbolic media and magnetic surface states

Metamaterials with magnetic properties have been widely investigated with rather complex twoand threedimensional resonant structures. Here we propose conceptually and demonstrate experimentally a mechanism for broadband optical magnetism in simpler one-dimensional systems. We experimentally demonstrate that alternating high-index dielectric/metal multilayer hyperbolic metamaterials can exhibit a strong magnetic response including variously μ >1 to μ < 0 . By engineering the electric permittivity as well, we reveal an epsilon and mu near zero regime. We show that modifications of internal metamaterial structure can lead to either type I or type II magnetic hyperbolic dispersion, thereby generalizing the notion of a hyperbolic metamaterial to encompass both TE and TM polarizations in simple multilayer geometries. Finally, we show that a negative magnetic response can give rise to TE interface-bound states, analogous to their TM counterparts, surface plasmon polaritons. PACS numbers: 78.67.Pt, 73.20.Mf, 75.30.Gw, 78.20.Ls Main Text and Figures The interaction of matter with magnetic fields is usually described in terms of the magnetic permeability μ . In the optical regime, natural materials do not exhibit magnetic properties, as famously expressed in the textbook by Landau and Lifshitz: “there is no meaning in using the magnetic susceptibility from the optical frequencies onward, and in discussing such phenomena, we must put μ = 1 ”. The lack of natural optical magnetism is associated with the weak magnetic coupling of the electromagnetic field with an atom, which is approximately 137 times weaker than the electric coupling. Therefore, the magnetization of natural materials typically vanishes beyond frequencies in the GHz range. The critical parameters for engineering the magnetic response of materials are their internal electronic spin configuration, in the microscopic scale, and the induced currents they support when illuminated with electromagnetic fields, in the mesoscopic scale, in which metamaterials operate. The absence of natural magnetism at optical frequencies has motivated metamaterials researchers to seek for artificial structures exhibiting magnetic properties. During the past decade, there have been numerous theoretical and experimental demonstrations of optical magnetism However up until now, the metamaterial structures that have been explored often require rather complex resonant geometries, for example arrays of paired thin metallic strips, split ring resonators or fishnet structures. Dielectric nanoparticles and nanorods 13 have been the building blocks