Switching Energy of Ferromagnetic Logic Bits
  Power dissipation in switching devices is believed to be the single most important roadblock to the continued down scaling of electronic circuits. There is a lot of experimental effort at this time to implement switching circuits based on magnets and it is important to establish power requirements for such circuits and their dependence on various parameters. This paper analyzes switching energy which is dissipated in the switching process of single domain Ferromagnets used as cascadable logic bits. We obtain generic results that can be used for comparison with alternative technologies or guide the design of magnet based switching circuits. Two central results are established. One is that the switching energy drops significantly if the ramp time of an external pulse exceeds a critical time. This drop occurs more rapidly than what is normally expected of adiabatic switching for a capacitor. The other result is that under the switching scheme that allows for logic operations, the switching energy can be described by a single equation in both fast and slow limits. Furthermore, these generic results are used to quantitatively examine the possible operation frequencies and integration densities of these logic bits which show that nanomagnets can have scaling laws similar to CMOS technology. 
Behtash Behin-Aein, Sayeef Salahuddin and Supriyo Datta