Quantum Pumping of Charge and Spin Currents in Graphene Nano Ribbons
Journal Title: Bulletin of Pure and Applied Sciences Sec. D – Physics - Year 2018, Vol 37, Issue 2
Abstract
We have studied the case of nonmagnetic leads in which only part of the graphene nano ribbons is subjected to an ac gate voltage to break the left-right spatial symmetry. It was shown that peaks of the negative (positive) charge pumping current appear at the Fermi energies around the energy maximums (minimums) of the sub-bands in the ac field free region of the graphene nano ribbon. In the case of ferromagnetic leads with the lead magnetizations being antiparallel in order to break the left-right symmetry. It was found that a pure spin current can be achieved when the whole graphene nanoribbon was under an ac gate voltage. It was also found that peaks in the negative spin pumping current at the Fermi energies around the energy maximums of the majority spin sub-bands in the ferro-magnetic leads. We have shown that the pumping current increases monotonically with the ac field strength due to the enhanced photon-assisted transmissions. We found that at low ac field frequency, the pumping currents exhibited non-monotomic frequency dependence. This is due to the competition of the weakened photon assisted transmissions and the increasing energy space of the states contributing to the pumping current. AT high frequency, the pumping current decreased monotonically with increasing frequency because the ac field became in effective in existing photons. Our results showed that the Fermi energies corresponding to peaks are influenced by the energy level shifting in the ac field free region, but independent of that in the ac field applied region.
Authors and Affiliations
Gautam Kumar Sinha
Keywords
Related Articles
- EP ID EP528861
- DOI 10.5958/2320-3218.2018.00010.6
- Views 138
- Downloads 0
Photoionization Spectroscopy of Lithium, Sodium and Potassium Nanoparticles in a Beam for the Metallic Work Function
We have used a modified particle source with a temperature controlled nozzle to measure the temperature dependence of the work function for Lithium, Sodium and Potassium. The temperature dependence of the work function a...
Resonant Features in Bilayer Nanoribbons in a Single Mode Regime with a Short Range Defect
We have studied resonant features in bilayer nanoribbon in a single mode regime with a short range defect. We have found the effect of edge disorder on the transport properties of a graphene nanoribbons and bilayer graph...
Rotating MHD Flow: An Exact Solution by Hodograph Transformation
The motion of a homogenous, rotating, incompressible, second grade fluid with finite electrical conductivity through porous media in the presence of transverse magnetic field has been considered. For steady plane transve...
Nonperturbative Contributions to the Massive Propagator in a Class of Strong Interactions
The nonperturbative contribution to the correlation of gluon field strengths is computed within the field theory limit of a string diagrammatic expansion
Quantum Pumping of Charge and Spin Currents in Graphene Nano Ribbons
We have studied the case of nonmagnetic leads in which only part of the graphene nano ribbons is subjected to an ac gate voltage to break the left-right spatial symmetry. It was shown that peaks of the negative (positive...