Biquadratic coupling dependence on spacer layer thickness for Fe/Cr/Fe

We report on exchange coupling properties in sputtered Fe(40 Å)/Cr(t)/Fe(40 Å) trilayers. By fitting Brillouin light scattering, ferromagnetic resonance and magneto-optical Kerr-effect data to theoretical expressions, the exchange coupling parameters J1 and J2 can be reliably extracted. We have found that the ratio J1/J2 in the first negative peak is much bigger than recently reported. The FMR low-temperature measurements show a behavior which depends on the Cr layer thickness. © 1998 Elsevier Science B.V. All rights reserved.