薄膜矫顽力和磁各向异性方向的电场调控

We report the effect of electric fields on magnetic coercive force (Hc) and uniaxial magnetic anisotropy (UMA) orientation of polycrystalline Ni film grown on unpoled (011) [Pb(Mg1/3Nb2/3)O3]1-x-[PbTiO3]x (PMN-PT) single crystal substrate. The magnetic hysteresis loops of Ni film demonstrate that the charge of coercive force and small rotation of UMA are proportional to the reversible strain of substrate, which is induced by electric fields. It is revealed that the magnetic properties can then restore to the original state by gradually tuning a periodic electric field, mainly driven by strain-mediated magnetoeletric coupling in Ni/Ag/PMN-PT/Ag heterostructure. The poled PMN-PT produces strains, under the electric field in the range of -4.2 kV/cm≤E≤4.2 kV/cm, then transfers it to Ni film and thus changes its Hc and UMA. The variations of in-plane Hc, as well as the strain, present butterfly pattern versus electric field applied at two mutually orthogonal directions which are 45° angle to [100] direction. In addition, both the change of Hc and strain show asymmetric feature in two orthogonal directions, which can be resulted to that the UMA of Ni has a small angle rotation from -12° to 1°, and return to -6° as the electric field decreases. The effective manipulation of magnitude and orientation of magnetic anisotropy via magnetoeletric coupling in FM/FE heterstrctures is an important step towards controlling the tunnel magnetoresistance of magnetic tunnel junctions.