K. Cherifi

57Fe Mössbauer spectroscopy from Tb/Fe and Er/Fe multilayers

Mossbauer spectroscopy was carried out on Tb/Fe and Er/Fe multilayers. The dependence of the extension of the interface on the substrate temperature during the deposition process and its magnetic behaviour are shown. Easy plane of magnetization and perpendicular easy axis of magnetization have been observed in Er/Fe and Tb/Fe multilayers respectively. The effects of the ion anisotropy and of the thickness of the layers are discussed.

Direct Evidence of the Twisted State in Ferrimagnet Gd/Fe Multilayers by Mössbauer Spectroscopy

Magnetic texture of a Gd(84 A)/Fe(42 A) multilayered film has been investigated through 57Fe Mossbauer spectroscopy by using a 45° transmission geometry. The aligned and twisted states expected from simulations have been observed microscopically. The canting angles in the twisted state have been determined.

Magnetic structure of Gd/Fe multilayers

Abstract In Gd/Fe multilayers, Fe and Gd tend to couple antiferromagnetically and to form giant ferrimagnets. Experimental magnetic phase diagrams of Fe/Gd multilayers are presented as a function of the layer thicknesses. The results are in accordance with calculations which showed that the critical field for the occurrence of the ‘twisted state’ increases when the layer thicknesses decrease.

Low angle polarized neutron diffraction from Tb/Fe multilayers

Abstract Low angle polarized neutron scattering experiments have been performed on a Tb(61 A)/Fe(55A) multilayer. The evolution of the intensities ( I + and I - ) of the first peak shows that the average magnetizations of Tb and Fe are in the applied field direction. The intensities of the second and the third peaks indicate that there is an interface effect which is going along with the terbium magnetization. It is presumably the result of the antiferromagnetic coupling between iron and terbium.

Magnetization study of Er/Fe multilayers

Abstract The thermal variation of the magnetization of Er/Fe multilayers has been studied. Above 85 K erbium is paramagnetic except for one erbium atomic layer located at the interface. At low temperature, the average magnetizations of iron and erbium layers are in the field direction. The antiferromagnetic coupling between the elements keeps the moments of some erbium layers antiparallel to the iron magnetization at the interface.

Mise en évidence d'un état magnétique non colinéaire dans les multicouches Fe/Gd

In the Fe/Gd multilayered system the magnetic moments are constrained to be in the film plane owing to dominant shape anisotropy, provided the absence of crystal field effects upon the S state of Gd 3+ . The in-plane magnetic structure versus an external field applied parallel to the plane is studied through magnetization, magnetoresistance measurements and 57 Fe MOssbauer spectroscopy. The transition from the «aligned state» to a «twisted state» is evidenced at a critical H * field for a Fe(42A)/Gd(84A) sample. It turns out that H * depends upon temperature and respective Fe-Gd submagnetizations. The «twisted state» is favoured at the compensation temperature