  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.
