Controllable Magnetic Anisotropy of Ferromagnet/Antiferromagnet Bilayers Coupled with Piezoelectric Strain

Coupling of magnetoelastic and piezoelectric effects is achieved with the ferromagnetic (FM) Co60Fe20B20/antiferromagnetic (AFM) Co0.7Ni0.3O bilayers deposited on the surface of piezoelectric single crystalline substrate. Piezoelectric strain of the substrate is successfully transferred to the magnetic layers, and controllable variation of magnetic anisotropy in response to the elastic deformation is demonstrated in the M-H loops measured at various azimuthal angles with respect to the direction of AFM spin alignment. Magnetic behaviors of the exchange coupled bilayers can be understood by considering the competition of many magnetic anisotropy energies within the magnetic film based on the modified Meiklejohn and Bean (MB) model. From the comparison of experimentally measured results with the modified MB model, it is found that the strain in the film from the substrate effectively introduces additional uniaxial anisotropy in the FM layer with its anisotropy direction determined by the direction of the applied strain.