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

Abstract
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 Gd³⁺. The in-plane magnetic structure versus an external field applied parallel to the plane is studied through magnetization, magnetoresistance measurements and ⁵⁷Fe Mössbauer spectroscopy. The transition from the "aligned state" to a "twisted state" is evidenced at a critical H* field for a Fe(42 Å)/Gd(84 Å) sample. It turns out that H* depends upon temperature and respective Fe-Gd submagnetizations. The "twisted state" is favoured at the compensation temperature.