Luis Rosales | Searcharxiv

arXiv2018

Thermopower of Graphene Nanoribbons in the Pseudodiffusive Regime

Thermoelectric measurements for graphene ribbons are currently performed on samples that include atomic disorder via defects and irregular edges. In this work, we investigate the thermopower or Seebeck coefficient of graphene ribbons within the linear response theory and the Landauer formalism, and we consider the diffusive regime taken as a limit of the ribbon aspect ratio. We find that the thermopower and the electronic conductivity depend not only on the aspect ratio, but also on chemical potential and temperature, which are set here as key parameters. The obtained numerical results with temperature and doping are brought into contact with the thermoelectric measurements on disordered graphene ribbons with good agreement.

cond-mat.mes-hall↗

arXiv2011

Transport properties of graphene quantum dots

In this work we present a theoretical study of transport properties of a double crossbar junction composed by segments of graphene ribbons with different widths forming a graphene quantum dot structure. The systems are described by a single-band tight binding Hamiltonian and the Green's function formalism using real space renormalization techniques. We show calculations of the local density of states, linear conductance and I-V characteristics. Our results depict a resonant behavior of the conductance in the quantum dot structures which can be controlled by changing geometrical parameters such as the nanoribbon segments widths and relative distance between them. By applying a gate voltage on determined regions of the structure, it is possible to modulate the transport response of the systems. We show that negative differential resistance can be obtained for low values of gate and bias voltages applied.

cond-mat.mes-hall↗