Fourfold in-plane magnetic anisotropy in epitaxial Fe(110)/Cu(001) and Fe (110)/Ni (001) bilayers

Epitaxial Fe(110) films with thicknesses of 100-800 nm on Cu(001) and Ni(001) buffer layers grown on MgO(001) substrates have been fabricated. These films contain Fe(110) crystallites which are in the Pitsch orientation relationship. Magnetization and the fourfold in-plane magnetic anisotropy constants of these films have been determined by torque measurements. All the samples under study are characterized by a fourfold magnetic anisotropy with easy axes parallel to the [100] and [010] directions of Cu(001) and Ni(001) layers. The measured values of the constant for Fe(110)/Cu(001) are found to depend on deposition temperature; a maximum value of (2.5 +/- 0.1) x 10(5) erg/cm(3) is reached after annealing at 600 degrees C. The in-plane torque measurements on Fe(110)/Ni(001) bilayers obtained at 300 degrees C, on the other hand, exhibit a constant value of (2.77 +/- 0.1) x 10(5) erg/cm(3). Assuming an exchange interaction between the Fe(110) crystallites, which are in the Pitsch orientation relationship, the fourfold in-plane magnetic anisotropy has been calculated as 2.8 x 10(5) erg/cm(3). The deviations of the experimental values from the predicted one may be explained by the formation of a polycrystalline phase within the Fe(110) layer and a partial disorientation of the epitaxial crystallites. (C) 2010 Elsevier B.V. All rights reserved.