Phononic and magnonic dispersions of surface waves on a permalloy/BARC nanostructured array
1 Department of Physics, National University of Singapore, Singapore 117542, Singapore
2 Institute of Microelectronics, Agency for Science, Technology and Research, Singapore 117685, Singapore
3 Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
Nanoscale Research Letters 2013, 8:115 doi:10.1186/1556-276X-8-115Published: 2 March 2013
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. The magnonic band structure features near-dispersionless branches, with unusual vortex-like dynamic magnetization profiles, some of which lie below the highly-dispersive fundamental mode branch. Finite element calculations of the phononic and magnonic dispersions of the magphonic crystal accord well with experimental data.