Field-coupled nanomagnets for logic applications

Nanomagnets that exhibit only two stable states of magnetization can be used to store digital bits. This concept is already applied in today's magnetic random access memories. Interacting networks of such nanomagnets with physical spacing on the order of 10 nm between them have been proposed to propagate and process binary information by means of magnetic coupling. These networks, called magnetic quantum-dot cellular automata (MQCA), offer very low power dissipation and high integration density of functional devices. In addition, MQCA can operate over a wide temperature range from sub-Kelvin to the Curie temperature of the applied ferromagnetic material. We demonstrate room temperature operation of logic gates made of NiFe alloy and fabricated by electron-beam lithography on silicon. Dipolar ordering in the nanomagnet-networks is imaged by magnetic force microscopy, and the operation is explained by means of micromagnetic simulations.