Magnetic tunnel junctions based on FeCoB as a magnetic electrode and MgO as a tunneling barrier gained much attention because of their applications in random access memories and magnetic sensors in disk drives. In this work, the structural and magnetic properties of the MgO/FeCoB/MgO trilayer have been studied precisely under x-ray standing wave (XSW) conditions, where XSW is generated through a high-density (Pt) waveguide structure. The combined x-ray scattering and fluorescence data obtained under XSW conditions revealed the formation of a high-density FeCoB layer at the MgO/FeCoB interface (FeCoB-on-MgO) in the as-deposited trilayer. Diffusion of B from the FeCoB layer into MgO is attributed to the formation of Fe- and Co-rich high-density layer (B-deficient FeCoB layer) at the interface. Angular-dependent magnetism of the trilayer structure revealed the presence of in-plane magnetic anisotropy (IMA), which disappeared with thermal annealing at a temperature of 450 °C. Stress in B-deficient FeCoB layer at the interface is attributed to the origin of IMA through magneto-elastic anisotropy energy minimization. The disappearance of anisotropy after annealing is mainly due to the removal of long-range stress and the formation of crystalline bcc-FeCo phase.
Structural and magnetic asymmetry at the interfaces of MgO/FeCoB/MgO trilayer: Precise study under x-ray standing wave conditions
Note: This paper is part of the Special Topic on Advances in Multi-Scale Mechanical Characterization.
Md. Shahid Jamal, Pooja Gupta, Rakhul Raj, Mukul Gupta, V. R. Reddy, Dileep Kumar; Structural and magnetic asymmetry at the interfaces of MgO/FeCoB/MgO trilayer: Precise study under x-ray standing wave conditions. J. Appl. Phys. 21 June 2022; 131 (23): 235301. https://doi.org/10.1063/5.0092977
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