Giant room-temperature modulation of magnetic anisotropy by electric fields in CoFeB/(011)-PMN-PT multiferroic heterostructures with two distinct initial magnetic anisotropies

This paper reports that the in situ growth magnetic field (H-g) during magnetic-phase CoFeB deposition impacts the electric-field control of magnetic anisotropy in Co40Fe40B20/(011)-Pb(Mg1/3Nb2/3)(0.7)Ti0.3O3 [CoFeB/(011)-PMN-PT] composite multiferroic heterostructures at room temperature. In the H-g1 mode (in situ H-g along the [ 01 1 over bar ] direction of the ferroelectric PMN-PT substrate), the electric-field-controlled modulation ratios of the magnetic coercivity H-C and saturation magnetic field H-S are approximately -47% and +156%, respectively. However, in the H-g2 mode (in situ H-g along the [100] direction of the ferroelectric PMN-PT substrate) of the CoFeB/(011)-PMN-PT multiferroic heterostructure, the electric-field-controlled modulation ratios of the magnetic coercivity H-C and saturation magnetic field H-S can reach as high as +162% and +393%, respectively. Moreover, the electric-field-controlled magnetic coercive field H-C exhibits a butterfly shape when plotted versus the applied electric fields in both modes, which matches the in-plane butterfly strain loop of the ferroelectric PMN-PT substrate. However, the electric-field-controlled saturation magnetic field H-S presents a square loop, which is very consistent with the ferroelectric loop of the PMN-PT substrate. This result may be ascribed to the distinct pathway of the ferroelastic domain switching in the (011)-oriented PMN-PT substrate. This study provides a new idea for the design of spintronic devices based on multiferroic heterostructures.