Polar magneto-optical Kerr effect studies of interlayer exchange coupling in Fe/Tb bilayers and Fe/Au/Tb trilayers

Interlayer exchange coupling was studied. The investigations were carried out on bilayer (Fe/Tb) and trilayer (Fe/Au/Tb) ultrathin film structures. The films on silica substrate were prepared by electron-beam evaporation in an MBE system with a background pressure of (1 ·5) · 10⁻¹⁰ Torr and maintaining a pressure of (1 · 3) · 10⁻⁹ Torr during the film growth. To investigate these film structures polar magneto-optical Kerr effect was used. In bilayers the perpendicular magnetic anisotropy was observed. When a monolayer of Au was interposed at the interface, was observed to disappear. This is because of breaking the short-range interaction between Fe and Tb layers. Instead a long-range indirect exchange via nonmagnetic Au interlayer appears. The increase of Au interlayer thickness (3 · 35 Å) resulted in the oscillations of the Kerr angle. Analogous oscillations are distinctive to the RKKY model of interlayer exchange coupling

Interlayer coupling in Tb/Fe bilayers and Tb/Au/Fe trilayers with sharp or rough interface

Bilayer films Fe/Tb (Tb on Fe) having sharp and Tb/Fe (Fe on Tb) having rough interface were prepared by molecular beam epitaxy to study interlayer magnetic coupling. Magnetic properties of these bilayers were characterized ex situ using ferromagnetic resonance (FMR), polar magneto-optical Kerr effect and SQUID magnetometer. The resulting perpendicular magnetic anisotropy (PMA) is discussed as an effect of interlayer magnetic coupling. PMA was observed in rough as well as in sharp interfaces and the anisotropy energies were estimated. When a monolayer of Au was interposed at the interface of both kinds, PMA was observed to disappear and the overall magnetic moment increased. It was also shown that in ultrathin films demagnetization factor depends on the substrate roughness and should be considered in the FMR data. Bilayer films Fe/Tb (Tb on Fe) having a sharp interface and Tb/Fe (Fe on Tb) having a rough interface are prepared by molecular beam epitaxy to study the interlayer magnetic coupling. The magnetic properties of these bilayers are characterized ex situ using ferromagnetic resonance (FMR). The polar magnetooptical Kerr effect, and a SQUID magnetometer. The resulting perpendicular magnetic anisotropy (PMA) is discussed as an effect of the interlayer magnetic coupling. PMA is observed at rough as well as at sharp interfaces, and the anisotropy energies are estimated. When a monolayer of Au is interposed at either kind of interface, the PMA is observed to disappear and the overall magnetic moment increases. It is also shown that in ultrathin films the demagnetizing factor depends on the substrate roughness and should be taken into account in the FMR data