Feasibility testing for magneto-optic ring cellular automata.

摘要

The feasibility of a magnetic computation system was tested that consists of arranging thin film micromagnetic ring structures. Each ring is magnetized in a circular, vortex state in either the clockwise (CW) or counterclockwise (CCW) directions, allowing a bit of information to be stored as the vortex chirality. The basic logic functions necessary to demonstrate a computation system are accomplished by linking multiple rings together such that the vortex state in one ring induces vortex states of opposite chirality to its neighbors. This system is an example of a computational scheme known as magnetic cellular automata (MCA), where operations are performed via the placement of magnetic components that are coupled through magnetic interactions. In this case, individual rings transfer data through magnetic exchange interactions and the propagation of magnetic domain walls. The ability to both perform magnetic computations and store data locally may lead to applications such as radiation-robust chips and smart memory.;To test the feasibility of such a system, several basic functions inherent of a computation system were demonstrated. This included the NOT gate as well as a multiple purpose majority gate. Additionally, the ability to pass data through the analogue of a wire was tested along with data fan-out and the ability to introduce inputs to the system using global magnetic fields and current pulses. It was found that control of the device geometry and the propagation of domain walls are vital in demonstrating these functions. Analyses were carried on the scalability and power dissipation of such as system that showed promise in their ability to function as mesoscale devices with low power dissipation.;The magnetizations of all structures were characterized using the longitudinal magneto-optic Kerr effect (LMOKE) and global field actuation by focusing a laser over a magnetized ring and analyzing the reflected beam. Since the net magnetization of both the CW and CCW states is zero, optical coatings were applied to the magnetic structures to break the symmetry of the optical signal. This new technique enabled rapid characterization of the magnetization dynamics in the devices that were compared to micromagnetic simulations.