Domains in CoCr investigated by neutron depolarization

Polarized neutrons (λ = 0.47 nm) are transmitted through RF and magnetron sputtered CoCr films (0.3-5 μm thick) with the polarization vector in the plane or perpendicular to the plane of the film. In the former case we can deduce from the depolarization the effective height heffof the domains and from the angular dependence of the depolarization the section width δ (which is proportional to the domain width) in the remanent states after perpendicular and after in-plane saturation. As expected, heffappears to be larger after perpendicular saturation and for a film thickness h ∼ 400 nm, heffapproaches h. This is attributed to the disappearance of reversed spike domains in the thinnest films. The lower hefffound in magnetron films with a lower surface/bulk coercivity ratio is also consistent with spike domain theory. The section width δ is found to he proportional to hx with x depending on the preparation or magnetic history of the film between 0.6 and 0.8. For magnetron films δ is ∼ 1.5 as large as in RF films of equal thickness, in qualitative agreement only with the fact that K1is twice as large as for RF films.