Magnetoplasmonic nanostructures Nikolaos Stefanou Department of Solid State

Magnetoplasmonic nanostructures Nikolaos Stefanou Department of Solid State Physics National and Kapodistrian University of Athens

Magneto-optical response of materials z >0, dielectric <0, metallic losses

z eigenvectors eigenvalues LCP RCP longitudinal RCP LCP

Particle Plasmons: localized states of EM field, e. g. in a noble metal nanoparticle Ag

Circular Dichroism: Differential absorption of LCP and RCP light TEM 40 nm F. Pineider et al. , Nano Lett. 13, 4785 (2013) Applications for environmental sensors. Required strong fields > 10 T

Αg (40 nm) Co-Ag (28 nm 40 nm) Ag: strong plasmon resonances, weak magneto-optic effects Co: gyrotropic responce, strong magnetooptic effects, no plasmon resonances

Hydrid nanoparticles consisting magnetic core (Co) and plasmonic shell (Ag) L. Wang et al. , Nano Lett. 11, 1237 (2011)

Scattering from gyrotropic sphere with isotropic shell Host: Shell: Core: Boundary conditions scattering T matrix

Applications: nanoparticles Co-Ag : absorption cross section and electric field amplitude distribution (16 -40) nm (28 -40) nm

Circular dichroism of core-shell Co-Ag spheres (16 -40) nm (28 -40) nm

Diagonal (upper diagram) and nondiagonal (lower diagram) elements of the relative perimittivity tensor for magnetized cobalt Im Re g Re Im

Garnets, e. g. , Yttrium Iron Garnet §Ferrimagnetic material §Transparent for , low losses §YIG spheres commercially available §Large Faraday rotation §Saturation magnetization ØOptical and magneto-optical applications ØMicrowave filters TEM image of Bi: YIG nanospheres ØMagneto-optic devices T. Kim et al. , J. Nanopart. Res. 9, 737 (2007) ØSolid State lasers

Plasmon Hybridization Antibonding hybrid plasmon Bonding hybrid plasmon C. S. Levin et al. , ACS Nano 3, 1379 (2009)

Hybrid nanoparticles consisting of dielectric core (Bi: YIG) and plasmonic shell (Ag) (16 -40) nm (28 -40) nm

Circular dichroism of core-shell Bi: YIG-Ag spheres (16 -40) nm (28 -40) nm

Diagonal (upper diagram) and nondiagonal (lower diagram) elements of the relative perimittivity tensor for magnetized Bi: YIG

Light propagation in stratified media • conserved , , z

Scattering matrices of a 2 D periodic • array of scatterers conserved α Bloch theorem Layer-Multiple Scattering method N. Stefanou et al. , Computer Phys. Commun. 113, 49 (1998); 132, 189 (2000); Phys. Rev. B 73, 035115 (2006)

Faraday rotation Homogeneous Magnetic material

Hybrid core-shell nanoparticles Dielectric magnetic core-Metallic shell Plasmon mode localized in the magnetic core material

Core-shell nanoparticles Core Shell • Host medium Volume filling fraction 50%

Photonic band diagram of the homogenized crystal

Photonic band diagram of an fcc crystal Band hybridization d

Faraday rotation through an fcc (111) slab of 64 layers f

8 fcc (111) layers (a=34 nm) of Bi: YIG (12 nm) - Ag (15 nm) core-shell nanoparticles Exact Effective medium

B lack of time-reversal and space-inversion symmetries J. Sharma et al. , Science 323, 112 (2009) spectral nonreciprocity optical communications computing technologies one-way propagation

Nonreciprocal layer modes