Charge and Heat Transport in Low-dimensional Systems

DIPC Seminars

Davide Donadio, MPI for Polymer Research, Mainz, Germany
Donostia International Physics Center (DIPC).Paseo Manuel de Lardizabal, 4 (nearby the Facultad de Quimica), Donostia
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Charge and Heat Transport in Low-dimensional Systems The functionality of materials and devices essentially depends on their transport properties. Although the most exploited and best understood form of energy and information transport is so far electronic conduction, nanoscale science opened the way to alternatives, such as spin, mass and phonon transport, which may extend our present capabilities in exploiting renewable energies and information technologies. Here we utilize numerical atomistic simulations to describe two examples of unconventional transport properties in low-dimensional nanoscale systems: namely, proton transfer in water wires adsorbed on metals and heat transport graphene. In the first case we show that the interplay between hydrogen bonding between water molecules and the chemical interaction between water and the edge atoms of stepped metallic surfaces naturally generates favorable conditions for controlled one-dimensional proton (hole) transfer, making these systems viable candidates for ice-based electronics. The study on graphene aims at the fundamental understanding of heat transport in a realistic, experimentally viable two-dimensional system. We employ large scale molecular dynamics simulations to study thermal transport in suspended graphene under realistic circumstances, such as the presence of mechanical strain, isotopic mass disorder, and a wide temperature range. We find that the thermal conductivity of graphene is finite for unstrained systems and, under mild uniaxial tensile strain. On the other hand, we show that the thermal conductivity of graphene under larger (>2%) tensile strain diverges, irrespective of both temperature and isotopic disorder. These results are discussed in relation to both experiments and 2D ideal models used in statistical physics.