MOKE Measurements Research Articles

Role of interface alloying in Fe whisker/Cr/Fe(001) structures, angular-resolved Auger electron and MOKE studies

Angular-resolved Auger electron spectroscopy (ARAES) studies were carried out at Fe whisker/Cr(001) interfaces. The interfaces were prepared at 100, 180, 246 and 296°C. Interface alloying increases progressively with increasing substrate temperature. The MOKE measurements on Fe whisker/Cr/Fe(001) showed a strong dependence of the bilinear exchange coupling on interface alloying.

Spin-valve effect in non-coupled FeNi/Cu/FeNi sandwiches

Sandwiches containing FeNi and Cu layers were grown by rf and dc sputtering in a magnetic field of 30 Oe. After deposition of the first FeNi and Cu layers the sample was rotated 90° in the magnetic field. Due to the relatively thick Cu interlayer (60 Å) we get an uncoupled system with two different easy axis orientations in the upper and lower FeNi layers. MOKE and MR measurements show expected behaviour, although the spin-valve MR effects are relatively small and of the order of the AMR. A simple theoretical separation of the two MR effects was successful.

A magneto-optic technique for studying magnetization reversal processes and anisotropies applied to Co/Cu/Co trilayer structures

We report the magnetization reversal and magnetic anisotropy behavior of ultrathin Co/Cu(111)/Co (dCu=20 and 27 Å) trilayer structures prepared by MBE on a 500-Å Ge/GaAs(110) epilayer. We describe an arrangement in which the magnetization components parallel and perpendicular to the applied field are both determined from longitudinal MOKE measurements. For the samples examined, coherent rotation of the magnetization vector is observed when the magnetic field is applied along the hard in-plane anisotropy axis, with the magnitude of the magnetization vector constant and close to its bulk value. Results of micromagnetic calculations closely reproduce the observed parallel and perpendicular magnetization loops, and yield strong uniaxial magnetic anisotropies in both layers while the interlayer coupling appears to be absent or negligible in comparison with the anisotropy strengths. An absence of antiferromagnetic (AF) coupling has been observed previously [W. F. Egelhoff, Jr. and M. T. Kief, Phys. Rev. B 45, 7795 (1992)] in contrast to recent results, indicating that AF coupling [M. T. Johnson et al., Phys. Rev. Lett. 69, 969 (1992)] and GMR [D. Grieg et al., J. Magn. Magn. Mater. 110, L239 (1992)] can occur in Co/Cu(111)/Co structures grown by MBE, but these properties are sensitively dependent on growth conditions. The absence of coupling in our samples is attributed to the presence of a significant interface roughness induced by the Ge epilayer. The uniaxial anisotropies are assumed to arise from strain or defects induced in the film.