Quantum nanojunctions as spintronic logic operators: Gate response in a two input ballistic interferometer

We discuss the electron transport for a spin polarized current through a ballistic quantum nanojunction formed by two quantum dots (QDs) and a semiconducting quantum wire. We explore the possibilities of designing spintronic logic gates at the nano-scale level derivedfrom this device. Just one electron with a given spin polarization fills each QD and the stationary binary digit consists of the spin-up and spin-down of a single electron. Thus the spin polarizations of those electrons are treated as the two inputs of the gates. The AND, XOR, XNOR, and NOR gate response in the system is investigated beginning with the calculation of the low bias conductance-energy characteristic in the ballistic regime. Our study suggests that, for an appropriate choice of the working Fermi energy and of the distance between the QDs, a high output current (in the logical sense) appears for certain combinations of the inputs while it vanishes for others. It clearly demonstrates the logic gate behavior and this aspect may be utilized in designing a spintronic logic operator. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3598127]