Periodicity Dependence of Magnetic Anisotropy and Magnetization of FeCo Heterostructure

Abstract

The magnetic anisotropy energy (MAE) and the saturation magnetization Bs of (110) FenCon heterostructures with n = 1, 2, and 3 are investigated in first-principles within the density functional theory by using the precise full-potential linearized augmented plane wave (FLAPW) method. We compare the results employing two different exchange correlation potentials, that is, the local density approximation (LDA) and the generalized gradient approximation (GGA), and include the spin-orbit coupling interaction of the valence states in the second variational way. The MAE is found to be enhanced significantly compared to those of bulk Fe and Co and the magnetic easy axis is in-plane in agreement with experiment. Also the MAE exhibits the in-plane angle dependence with a two-fold anisotropy showing that the [1Ī0] direction is the most favored spin direction. We found that as the periodicity increases, (ⅰ) the saturation magnetization Bs decreases due to the reduced magnetic moment of Fe far from the interface, (ⅱ) the strength of in-plane preference of spin direction increases yielding enhancement of MAE, and (ⅲ) the volume anisotropy coefficient decreases because the volume increase outdo the MAE enhancement.