Tuning of uniaxial magnetic anisotropy in amorphous CoFeB films

• Published in: Journal of physics. Condensed matter Vol. 25; no. 10; p. 106003
• Main Authors: Cui, B, Song, C, Wang, Y Y, Yan, W S, Zeng, F, Pan, F
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 13.03.2013; Institute of Physics
• Subjects: Buffers; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Copper; Crystallinity; Exact sciences and technology; Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance; Magnetic anisotropy; Magnetic properties and materials; Magnetic properties of monolayers and thin films; Magnetic properties of surface, thin films and multilayers; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Magnetization reversal; Orbitals; Physics; Tantalum; Tuning; Buffer layer; Magnetization reversal; Polycrystals; Amorphous alloy; Iron alloys; Crystallinity; Boron alloys; Magnetic tunnel junction; Thin films; Ferromagnetic resonance; Transmission electron microscopy; Magnetic anisotropy; Angular momentum; Magnetic circular dichroism; Microstructure; Cobalt alloys; Transition element alloys
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/25/10/106003

We demonstrate that the uniaxial magnetic anisotropy (UMA) of amorphous CoFeB films can be tuned by crystallinity and orbital moment ratio, combining the results of magnetization reversal and ferromagnetic resonance with high-resolution transmission electron microscopy, x-ray-absorption near-edge structure and x-ray magnetic circular dichroism. Isotropic polycrystalline buffers of tungsten (W), tantalum (Ta), and copper (Cu) between CoFeB and Si(100) substrates have direct and crucial bearing on the interfacial microstructure and orbital moment ratio. Compared with Ta and Cu buffer, CoFeB with W buffer exhibits obvious UMA and has lower crystallinity at the interface and higher orbital moment. Amorphous phase distributed homogeneously in CoFeB film grown on W buffer contributes to improve the easy-axis squareness with a sharp magnetization reversal. Our demonstrations not only realize effective tuning of UMA in amorphous CoFeB, but also provide an appealing alternative buffer (W) for CoFeB-based magnetic tunnel junctions.