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° 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 μs m⁻¹, 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.