  All-electrical and programmable manipulations of ferromagnetic bits are
highly pursued for the aim of high integration and low energy consumption in
modern information technology. Methods based on the spin-orbit torque switching
in heavy metal/ferromagnet structures have been proposed with magnetic field,
and recently are heading toward deterministic switching without external
magnetic field. Here we demonstrate that an in-plane effective magnetic field
can be induced by an electric field without breaking the symmetry of the
structure of the thin film, and realize the deterministic magnetization
switching in a hybrid ferromagnetic/ferroelectric structure with Pt/Co/Ni/Co/Pt
layers on PMN-PT substrate. The effective magnetic field can be reversed by
changing the direction of the applied electric field on the PMN-PT substrate,
which fully replaces the controllability function of the external magnetic
field. The electric field is found to generate an additional spin-orbit torque
on the CoNiCo magnets, which is confirmed by macrospin calculations.
