Can spintronic field effect transistors compete with their electronic counterparts?

Current interest in spintronics is largely motivated by a belief that spin based devices (e.g. spin field effect transistors) will be faster and consume less power than their electronic counterparts. Here we show that this is generally untrue. Unless materials with extremely strong spin orbit interaction can be developed, the spintronic devices will not measure up to their electronic cousins. We also show that some recently proposed modifications of the original spin field effect transistor concept of Datta and Das [Appl. Phys. Lett., Vol. 56, 665 (1990)] actually lead to worse performance than the original construct.