title: Switching of perpendicularly polarized nanomagnets with spin orbit torque without an external magnetic field by engineering a tilted anisotropy.
abstract: Spin orbit torque (SOT) provides an efficient way to significantly reduce the current required for switching nanomagnets. However, SOT generated by an in-plane current cannot deterministically switch a perpendicularly polarized magnet due to symmetry reasons. On the other hand, perpendicularly polarized magnets are preferred over in-plane magnets for high-density data storage applications due to their significantly larger thermal stability in ultrascaled dimensions. Here, we show that it is possible to switch a perpendicularly polarized magnet by SOT without needing an external magnetic field. This is accomplished by engineering an anisotropy in the magnets such that the magnetic easy axis slightly tilts away from the direction, normal to the film plane. Such a tilted anisotropy breaks the symmetry of the problem and makes it possible to switch the magnet deterministically. Using a simple Ta/CoFeB/MgO/Ta heterostructure, we demonstrate reversible switching of the magnetization by reversing the polarity of the applied current. This demonstration presents a previously unidentified approach for controlling nanomagnets with SOT.
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720;
authors.forename: Long
authors.identifier: http://orcid.org/0000-0003-1703-4074
authors.initials: L
authors.lastname: You
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720;
authors.forename: OukJae
authors.initials: O
authors.lastname: Lee
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720;
authors.forename: Debanjan
authors.initials: D
authors.lastname: Bhowmik
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720;
authors.forename: Dominic
authors.initials: D
authors.lastname: Labanowski
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720;
authors.forename: Jeongmin
authors.initials: J
authors.lastname: Hong
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720;
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Bokor
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 sayeef@berkeley.edu.
authors.forename: Sayeef
authors.initials: S
authors.lastname: Salahuddin
keywords: nanomagnets; perpendicular anisotropy; spin orbit torque