  A new spin based logic device is proposed. It is comprised of a common free
ferromagnetic layer separated by a tunnel junction from three inputs and one
output with separate fixed layers. It has the functionality of a majority gate
and is switched by spin transfer torque. Validity of its logic operation is
demonstrated by micromagnetic simulation. A version of such devices with
perpendicular magnetization is examined. Switching encompasses moving domain
walls. The device reuses most of the materials and structures from spin torque
RAM, and is entirely compatible with CMOS technology.
