  Room temperature operation of a spin exclusive or (XOR) gate was demonstrated
in lateral spin valve devices with nondegenerate silicon (Si) channels. The
spin XOR gate is a fundamental part of the magnetic logic gate (MLG) that
enables reconfigurable and nonvolatile NAND or OR operation in one device. The
device for the spin XOR gate consists of three iron (Fe)/cobalt (Co)/magnesium
oxide (MgO) electrodes, i.e., two input and one output electrodes. Spins are
injected into the Si channel from the input electrodes whose spin angular
momentum corresponds to the binary input 1 or 0. The spin drift effect is
controlled by a lateral electric field in the Si channel to adjust the spin
accumulation voltages under two different parallel configurations,
corresponding to (1, 1) and (0, 0), so that they exhibit the same value. As a
result, the spin accumulation voltage detected by the output electrode exhibits
three different voltages, represented by an XOR gate. The one-dimensional spin
drift-diffusion model clearly explains the obtained XOR behavior. Charge
current detection of the spin XOR gate is also demonstrated. The detected
charge current has a maximum of 0.94 nA, the highest value in spin XOR gates
reported thus far. Furthermore, gate voltage modulation of the spin XOR gate is
also demonstrated, which enables operation of multiple MLG devices.
