  Heavy metal/ferromagnetic layers with perpendicular magnetic anisotropy (PMA)
have potential applications for high-density information storage in racetrack
memories and nonvolatile magnetic random access memories. Writing and erasing
of information in these devices are carried out by domain wall (DW) motion and
deterministic magnetization switching via electric current generated spin
orbital torques (SOTs) with an assistance of in-plane bias field to break the
symmetry. Improvements in energy efficiency could be obtained when the
switching of perpendicular magnetization is controlled by an electric current
generated SOTs without the in-plane bias fields. Here, we report on reversible
electric-current-driven magnetization switching through DW motion in Pt/Co/Cr
trilayers with PMA at room temperature due to the formation of homochiral
Neel-type domain, in which an in-plane effective Dzyaloshinskii-Moriya
interaction field exists. Fully deterministic magnetic magnetization switching
in this trilayers is based on the enhancement of SOTs from a dedicated design
of Pt/Co/Cr structures with two heavy metals Pt and Cr which show the opposite
sign of spin Hall angles. We also demonstrated that the simultaneously
accompanying Joule heating effect also plays a key role for field-free
magnetization switching through the decrease of the propagation field.
