Theoretical imaging of current profiles in two-dimensional devices

This paper addresses in a concise and rigorous way the basic tools for the study of local longitudinal and transverse microscopic currents in two-dimensional devices. The emphasis is on the optimized use of the Keldysh nonequilibrium Green's function theory together with the tight-binding representation of the electronic system. We elaborate general analytic expressions of current profiles, useful for modeling and simulating the local site-to-site flow of carriers; furthermore, in broken time-reversal symmetry, the formalism discerns unambiguously persistent and transport contributions to the bond currents. Our approach achieves a workable theoretical imaging, resolved in space and energy, of the microscopic currents through mesoscopic devices.