Switching of Perpendicularly Polarized Nanomagnets with Spin Orbit Torque without an External Magnetic Field by Engineering a Tilted Anisotropy

TL;DR

This paper demonstrates a method to switch perpendicularly polarized nanomagnets using spin orbit torque without external magnetic fields by engineering a tilted anisotropy, enabling deterministic control for high-density data storage.

Contribution

It introduces a novel approach to achieve deterministic switching of perpendicular nanomagnets with SOT by tilting the magnetic anisotropy, eliminating the need for external magnetic fields.

Findings

Reversible switching of magnetization demonstrated in Ta/CoFeB/MgO/Ta heterostructure.

Tilted anisotropy breaks symmetry, enabling deterministic switching.

Method reduces energy and complexity for magnetic memory devices.

Abstract

Spin orbit torque (SOT) provides an efficient way of generating spin current that promises to significantly reduce the current required for switching nanomagnets. However, an in-plane current generated SOT 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 ultra-scaled dimensions. Here we show that it is possible 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 film-normal. 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 new approach for controlling nanomagnets with spin orbit torque.