  A mechanism of current-induced magnetization reversal based on the parametric
resonance is described. The source of the magnetization reversal is a
current-induced magnetic field, which is applied perpendicularly to the easy
axis of magnetic anisotropy of a ferromagnetic nanomagnet. The current-induced
magnetic field was measured in a FeCoB nanomagnet to be 60 Gauss at a current
density of 65 mA/um2. Two mechanisms of the magnetization reversal are
described and calculated. The first mechanism is the reversal by a RF
electrical current, which modulated at a frequency close to the precession
frequency of the nanomagnet. The second mechanism is the reversal by a DC
electrical current, in which the magneto-resistance and the current dependency
of the induced magnetic field create a positive feedback loop, which amplifies
a random tiny thermal fluctuation into a large magnetization precession leading
to the magnetization reversal. The combination of the proposed mechanism with
conventional magnetization-reversal mechanisms such as the Spin Torque and the
Spin-Orbit Torque can improve the performance of a Magnetic Random Access
Memory.
