The effect of annealing on the junction profile of CoFeB/MgO tunnel junctions

Abstract

The tunnelling magnetoresistance of CoFeB/MgO tunnel junctions is exceptionally high, although the electrodes and the barrier are grown at room temperature in the amorphous state. For their functionality annealing steps up to high temperatures are required. We have analyzed in detail the changes in the chemical and magnetization profile upon annealing up to 360°. The multilayers used for this study are similar to those which are used in magnetic tunnel junctions, however with five repeats. In particular, we have used hard non-resonant and soft resonant magnetic x-ray scattering in order to unravel any changes upon annealing. The multilayers exhibit superior structural quality, which hardly changes with annealing. Surprisingly, only little recrystallization of the CoFeB and the MgO layers can be discerned by x-ray diffraction.

Contributions of Co and Fe orbitals to perpendicular magnetic anisotropy of MgO/CoFeB bilayers with Ta, W, IrMn, and Ti underlayers

“…This indicates that both Co and Fe are predominantly metallic phases, i.e., no significant oxidized phase was formed during annealing. It has been reported that vacuum annealing can reduce the Co and Fe oxide phases, 28,29) which is a possible reason for our results. Therefore, the main reason for the observed decrease in the M s value is not the oxidization of CoFeB.…”

ALICE—An advanced reflectometer for static and dynamic experiments in magnetism at synchrotron radiation facilities

“…6(a). 46 Reflectivity scans (θ − 2θ scans) were recorded by tuning the photon energy to the Co L 3 resonance edge while magnetizing the sample in positive and negative saturating magnetic fields. This type of measurement is sensitive to the out-of-plane structural and magnetic correlation while probing the component of the magnetization vector in the scattering plane.…”

“…However, this normalized asymmetry is not entirely magnetic in origin as it would be for PNR, but a convolution of charge and magnetic cross section. From fitting the asymmetry, the magnetization profile in the multilayer can be gained, 46 as shown in Fig. 6(b).…”