Strong uniaxial magnetic anisotropy of nanostripes obtained by cutting thin epitaxial Fe layer using the atomic saw method

Abstract

We have applied the "atomic saw" method developed on semiconductor heterostructures to cut thin epitaxial Fe films deposited on (001) MgO substrate into Fe nanostripes. This method is based on dislocation slipping. We have controlled the slip along the (110) MgO planes and obtained Fe stripes along the [110] direction. We present the magnetic study of 2- and 5-nm-thick Fe films which have been cut by this method, with a deformation up to 8%. The surface of the deformed film, studied by atomic force microscopy, is characterized by regular steps, a few nm high, and from 50 nm to 2 µm wide, depending on the slipping plane density. Strong uniaxial magnetic anisotropy has been observed by magneto-optical measurements. Surprisingly, the easy magnetic axis is perpendicular to the nanostripes. Various possible mechanisms are discussed. However, it results probably in the relaxation of the elastic strain field at the Fe/MgO interface.