A novel Spin Injection Field Effect Transistor

We describe a new Spin Injection Field Effect Transistor (SIFET) with a quasi one-dimensional semiconductor channel and ferromagnetic source/drain contacts. We show that even when the ferromagnetic contacts are non-ideal with less than 100% spin polarization, the spin injection efficiency from the source into the channel can be switched from nearly +100 % to nearly +100 % with a small swing in gate bias at a temperature of 0 K. This corresponds to switching from mostly majority spin injection to mostly minority spin injection at the source end. If the spin polarization in the drain has the same sign as that in the source, then the drain will preferentially transmit injected majority spins while blocking minority spins. Therefore, one can switch the drain current from a maximum value to nearly zero with the gate bias (if there is no spin relaxation in the channel), thereby realizing transistor action. The current modulation and transistor action deteriorate with increasing temperature.