  A new proposal is given for designing a non-volatile, completely spin logic
device, that can be reprogrammed for different functional classical logical
operations. We use the concept of bias driven spin dependent circular current
and current induced magnetic field in a quantum ring under asymmetric
ring-to-electrode interface configuration to implement all the Boolean
operations. We extend our idea to build two kinds of parallel computing
architectures for getting parallelized operations, all at a particular time.
For one case, different kinds of parallel operations are performed in a single
device, whereas in the other type all the possible inputs of a logic gate are
processed in parallel and all the outputs are read simultaneously. The
performance and reliability are investigated in terms of power, delay and
power-delay-product and finally the system temperature. We find that both the
individual and simultaneous logic operations studied here are much superior
compared to the operations performed in different conventional logic families
like complementary metal oxide semiconductor logic, transistor-transistor
logic, etc. The key advantage is that we can perform several logic operations,
as many as we wish, repeating the same or different logic gates using a single
setup, which indeed reduces wiring in the circuits and hence consumes much less
power. Our analysis can be utilized to design optimized logic circuits at
nano-scale level.
