Voltage-Controlled Rotation of Magnetic Anisotropy in the Ni90Fe10/BaTiO3(001) Heterostructure

Abstract: In this work, we demonstrate the voltage control of magnetic anisotropy in a strain-mediated Ni90Fe10/BaTiO3(001) heterostructure. In the pristine state of the heterostructure, the Magneto-Optical Kerr Effect measurements show a transcritical hysteresis loop for the Ni90Fe10 film, indicating a weak perpendicular anisotropy. This was further confirmed by X-ray Magnetic Circular Dichroism - Photoemission Electron Microscopy, revealing stripe domains in this film. X-ray diffraction analysis of the BaTiO3 substrate under varying electric fields was used to analyze the orientation of ferroelectric domains. These results indicated that BaTiO3 exhibits two distinct states depending on the applied electric field: one with domains aligned with the electric field and another with random domain orientation when the field is removed. After substrate poling, the Ni90Fe10 layer switches from weak perpendicular anisotropy to an in-plane uniaxial magnetic anisotropy, with the in-plane direction of anisotropy being controllable by 90{\deg} through an electric field. This effect is due to an efficient strain transfer from BaTiO3 to the Ni90Fe10 lattice, induced by ferroelectric polarization, as shown by XRD. Remarkably, this rotation of the magnetic anisotropy leads to an enhanced converse magnetoelectric coupling value of 1.43 {\mu}s/m, surpassing previously reported values for other BaTiO3-based heterostructures by an order of magnitude. These results emphasize the potential of Ni90Fe10 alloys for next-generation magnetoelectric devices.