No 1, Vol. 4, 2001 


Z.K. Wang¹, M.H. Kuok¹, S.C. Ng¹, H.J. Fan¹,
D.J. Lockwood², K. Nielsch³ and R.B. Wehrspohn³

1 Department of Physics, National University of Singapore,
Singapore 117542, Republic of Singapore
2 Institute for Microstructural Sciences, National Research Council,
Ottawa K1A 0R6, Canada
3 Max Planck Institute of Microstructure Physics,
Weinberg 2, D-06120 Halle, Germany


The magnetic and vibrational excitations of periodic arrays of Ni nanowires, in 1 µm-thick Al2O3 membranes on Al substrates, have been investigated by Brillouin scattering. Ni nanowires of 30 and 40 nm diameter and periodicity of 100 nm have been studied in a transverse magnetic field from 0- 0.4 T. The p-s polarized spectra feature three peaks, with Brillouin frequencies below 20 GHz, and whose intensities are strongly dependent on the applied magnetic field and whose Stokes/anti-Stokes intensity ratios are unequal. These results indicate that the three peaks are magnetic in origin. A surface acoustic wave on the Ni-filled Al2O3 structures is also observed in p-p polarized spectra, with a phase velocity of about 3400 m/s for the 30nm-diameter nanowire sample.

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