Study of domain structures in FeCo/TiZr multilayers by means of 3D neutron depolarisation

Multilayers of composition 60(Co 68Fe 31V 1/Ti 75Zr 25) sputtered on Si wafers are studied by 3D neutron depolarisation analysis at glancing angles between −6.5° and 6.5°, both in zero and non-zero magnetic field. As the sample is rotated over a full turn in its plane, a 360° rather than 180° period is observed. This suggests that the magnetisation inside the CoFe sublayers is inclined by a few degrees out of the sample plane. Neighbouring FeCo sublayers cooperate by dipolar forces to form a structure of “inclined slab domains” with mutually antiparallel overall magnetisation. The thickness of these slabs includes 10–20 bilayers. In the hysteresis loop with the field parallel to the FeCo magnetisation a high remanence is found; when the field is (in-plane but) perpendicular to the FeCo magnetisation, the dipolar coupling is suppressed and a magnetisation loop with a lower remanence is observed.