MAGNETIC AND ACOUSTIC EXCITATIONS IN
CONFINED NICKEL NANOWIRES
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
0.4 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.
full paper (pdf, 240 Kb)