ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Brillouin light scattering (BLS) was used to measure magnon frequency versus in-plane field H and in-plane wave vector for a Fe(38 A(ring))/Cr(13 A(ring))/Fe(38 A(ring)) thin film. Both easy [100] and hard [110] field directions were used. The in-plane wave vector was perpendicular to the field. The data were obtained with a high contrast multipass tandem 3+3 Sandercock Fabry–Perot interferometer, with a free spectral range of 30 GHz. The results were correlated with previous hysteresis measurements.1 In the low field region (H〈200 Oe), the magnon frequency decreases with increasing field in a manner consistent with soft mode behavior. The mode frequency in this low field region is slightly different on the Stokes (S) and anti-Stokes (AS) sides of the BLS spectra. At fields of 150–200 Oe one sees a cusp-like minimum in the magnon frequency field dependence. The S and AS frequencies also converge at this point. This is evidence for the antiparallel alignment of the two magnetizations of the Fe layers and the onset of canting.2 At higher fields (250–350 Oe) one sees a jump in frequency, followed by an apparent approach to saturation, and a further increase above 2 kOe. This behavior is basically the same for both field directions, but the frequencies are downshifted somewhat for the hard [110] direction. The wave-number k dependence is weak in the low field region. Above the jump, the magnon frequency shows a distinct increase with k. The substantial frequency increase with field above 2 kOe may indicate conversion to a surface mode character. This is consistent with the k dependence seen at high fields.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.353494
