Direct observation of the Dzyaloshinskii-Moriya interaction in a Pt/Co/Ni film.

The interfacial Dzyaloshinskii-Moriya interaction in an in-plane anisotropic Pt(4  nm)/Co(1.6  nm)/Ni(1.6  nm) film has been directly observed by Brillouin spectroscopy.

Phononic and magnonic dispersions of surface waves on a permalloy/BARC nanostructured array.

Phononic and magnonic dispersions of a linear array of periodic alternating Ni80Fe20 and bottom anti-reflective coating nanostripes on a Si substrate have been measured using Brillouin light scattering. The observed phononic gaps are considerably larger than those of laterally patterned multi-component crystals previously reported, mainly a consequence of the high elastic and density contrasts between the stripe materials. Additionally, the phonon hybridization bandgap has an unusual origin in the hybridization and avoided crossing of the zone-folded Rayleigh and pseudo-Sezawa waves.

Magnonic band structure investigation of one-dimensional bi-component magnonic crystal waveguides.

The magnonic band structures for exchange spin waves propagating in one-dimensional magnonic crystal waveguides of different material combinations are investigated using micromagnetic simulations. The waveguides are periodic arrays of alternating nanostripes of different ferromagnetic materials. Our results show that the widths and center frequencies of the bandgaps are controllable by the component materials, the stripe widths, and the orientation of the applied magnetic field.

Hypersonic vibrations of Ag@SiO2 (cubic core)-shell nanospheres.

The intriguing optical and catalytic properties of metal-silica core-shell nanoparticles, inherited from their plasmonic metallic cores together with the rich surface chemistry and increased stability offered by their silica shells, have enabled a wide variety of applications. In this work, we investigate the confined vibrational modes of a series of monodisperse Ag@SiO(2) (cubic core)-shell nanospheres synthesized using a modified Stöber sol-gel method. The particle-size dependence of their mode frequencies has been mapped by Brillouin light scattering, a powerful tool for probing hypersonic vibrations.

Nanostructured magnonic crystals with size-tunable bandgaps.

Just as a photonic crystal is a periodic composite composed of materials with different dielectric constants, its lesser known magnetic analogue, the magnonic crystal can be considered as a periodic composite comprising different magnetic materials. Magnonic crystals are excellent candidates for the fabrication of nanoscale microwave devices, as the wavelengths of magnons in magnonic crystals are orders of magnitude shorter than those of photons, of the same frequency, in photonic crystals. Using advanced electron beam lithographic techniques, we have fabricated a series of novel bicomponent magnonic crystals which exhibit well-defined frequency bandgaps.

Micro-brillouin study of the eigenvibrations of single isolated polymer nanospheres.

The localized acoustic modes of single isolated polymethyl methacrylate (PMMA) and polystyrene nanospheres have been studied by micro-Brillouin light scattering. The measured mode frequencies are analyzed on the basis of the Lamb theory formulated for a sphere under free boundary conditions. By measuring light scattering from single isolated particles, placed atop a piece of polished silicon wafer, the free-surface conditions are almost experimentally realized.

Collective spin waves in high-density two-dimensional arrays of FeCo nanowires.

Brillouin measurements have been made of the spin dynamics of high-density two-dimensional hexagonally ordered 20 nm diameter Fe48Co52 nanowire arrays, with various interwire spacings, as a function of longitudinal magnetic field. The experimental data are analyzed within the Arias-Mills theory based on interwire dipolar couplings in the arrays. The results provide conclusive evidence of collective spin waves arising from the dipolar coupling which is manifested as a reduction in spin wave frequency with decreasing interwire spacing.