Magneto-Electric Magnetic Tunnel Junction Logic Devices
A majority-logic gate, the ME-MTJ may also be used to realize a compact exclusive-OR (XOR) gate based on a single MTJ. For the XOR gate, the fixed ferromagnetic layer in the MTJ cell is replaced by another free ferromagnetic layer in contact with an ME layer. Hence, we can apply voltage to two terminals instead of the one utilized in the basic inverter/buffer version of the ME-MTJ. The logical operation is as follows. If the spin vectors in the top free FM layer are oriented parallel to the spin vectors in bottom free FM layer, then we get maximum current across the junction, imposing a bit ‘0’ at the output. When the orientation is anti-parallel, the current is minimum, thus imposing a bit ‘1’ at the output.