Fractional periodic persistent current in a twisted normal metal loop: an exact result

We explore a novel mechanism for control of periodicity in persistent current in a twisted normal metal loop threaded by a magnetic flux $\phi$. A simple tight-binding model is used to describe the system. Quite interestingly we see that, depending on the number of twist $p$, the persistent current exhibits $\phi_0/p$ ($\phi_0=ch/e$, the elementary flux-quantum) periodicity. Such fractional periodicity provides a new finding in the study of persistent current.Comment: 7 pages, 4 figure

Implementation of classical logic gates at nano-scale level using magnetic quantum rings: A theoretical study

We explore the possibilities of designing classical logic gates at nano-scale level using magnetic quantum rings. A single ring is used for designing OR, NOT, XOR, XNOR and NAND gates, while AND and NOR gate responses are achieved using two such rings and in all the cases each ring is threaded by a magnetic flux $\phi$ which plays the central role in the logic gate operation. We adopt a simple tight-binding Hamiltonian to describe the model where a magnetic quantum ring is attached to two semi-infinite one-dimensional non-magnetic electrodes. Based on single particle Green's function formalism all the calculations which describe two-terminal conductance and current through the quantum ring are performed numerically. The analysis may be helpful in fabricating mesoscopic or nano-scale logic gates.Comment: 19 pages, 25 figures, 7 table