35 research outputs found
Input-driven chaotic dynamics in vortex spin-torque oscillator
A new research topic in spintronics relating to the operation principles of
brain-inspired computing is input-driven magnetization dynamics in nanomagnet.
In this paper, the magnetization dynamics in a vortex spin-torque oscillator
(STO) driven by a series of random magnetic field are studied through a
numerical simulation of the Thiele equation. It is found that input-driven
synchronization occurs in the weak perturbation limit, as found recently. As
well, chaotic behavior is newly found to occur in the vortex core dynamics for
a wide range of parameters, where synchronized behavior is disrupted by an
intermittency. Ordered and chaotic dynamical phases are examined by evaluating
the Lyapunov exponent. The relation between the dynamical phase and the
computational capability of physical reservoir computing is also studied.Comment: 11 pages, 4 figure
Spintronic reservoir computing without driving current or magnetic field
Recent studies have shown that nonlinear magnetization dynamics excited in
nanostructured ferromagnets are applicable to brain-inspired computing such as
physical reservoir computing. The previous works have utilized the
magnetization dynamics driven by electric current and/or magnetic field. This
work proposes a method to apply the magnetization dynamics driven by voltage
control of magnetic anisotropy to physical reservoir computing, which will be
preferable from the viewpoint of low-power consumption. The computational
capabilities of benchmark tasks in single MTJ are evaluated by numerical
simulation of the magnetization dynamics and found to be comparable to those of
echo-state networks with more than 10 nodes.Comment: 13 pages, 5 figure