Digital logic using 3-terminal spin transfer torque devices
  We demonstrate for the first time that functionally complete digital logic can be created by using three terminal devices each consisting of a magnetic tunnel junction (MTJ) and spin transfer torque (STT) element with a shared free magnetic layer. Rather than the output of devices being high or low voltage levels, logical states are represented as output resistances which retain their state when unpowered. By cascading and clocking devices using a multi-phase clock, threshold logic can be used to implement functionally complete digital logic. Using this approach, a single device can act as an AND, NAND, OR, or NOR gate without the need for external circuitry. Required device parameters and tolerances are discussed. 
Benjamin Buford, Albrecht Jander, Pallavi Dhagat
cond-mat.mes-hall