Interference phenomena in open quantum systems: applications for molecular switches and thermoelectric devices

DIPC Seminars

Speaker

Daijiro Nozaki

When

2016/06/09
14:00

Place

Donostia International Physics Center

Add to calendar

iCal

Subscribe to Newsletter

Interference phenomena in open quantum systems: applications for molecular switches and thermoelectric devices Daijiro Nozaki Department of Theoretical Physics University of Paderborn Warburger Straße 100 33098 Paderborn, Nordrhein-westfalen, Germany Quantum interference effects in molecular devices has drawn increasing attention in the last decades because of unique features observed in conductance spectrum applicable to thermoelectric devices and molecular switches [1-3]. For the further development of single molecular devices exploiting QI effects, it is of great theoretical and practical interest to clarify the relationship between the line shape of conductance spectra including QI features and controlling parameters such as electronic structures (on-site energies and transfer integrals) and topologies of molecules. In this talk, first I present a simple graphical method (parabolic diagram) that we developed to visualize the relation between the electronic parameters and line shape of conductance spectrum influenced by QI effect in the molecular junction with a side group (T-shaped molecule) [4]. Next, we present systematic analysis of thermoelectric properties in a series of molecular junctions having different topologies and QI features in toy model basis [5]. We also shows recent result of switchable negative differential resistance (NDR) in porphyrine-based molecular devices [6]. Charge transport through a carbon-based molecular switch consisting of different tautomers of metal-free porphyrin embedded between graphene nanoribbons is studied by quilibrium Green's function formalism. Different low-energy and low-bias features are revealed, including NDR and antiresonances, both mediated by subtle quantum interference effects. Moreover, the molecular junctions can display moderate rectifying or nonlinear behavior depending on the position of the hydrogen atoms within the porphyrin core. We rationalize the mechanism leading to NDR and antiresonances by providing a detailed analysis of transmission pathways and frontier molecular orbital distribution. References: [1] S. V. Aradhya and L. Venkataraman, Nature Nanotechnol. 8, 399 (2013). [2] W. Hong, H. Valkenier, G. Mészáros, D. Z. Manrique, A. Mishchenko, A. Putz, P. M. García, C. J. Lambert, J. C. Hummelen, T. Wandlowski, Beilstein J. Nanotechnol. 2, 699 (2011). [3] C. M. Guédon, H. Valkenier, T. Markussen, K. S. Thygesen, J. C. Hummelen, S. J. van der Molen, Nature Nanotechnol. 7, 305 (2012). [4] DN, H. Sevinçli, S. M. Avdoshanko, R. Gutierrez, G. Cuniberti, PCCP 15, 13951 (2013). [5] DN, S. M. Avdoshanko, H. Sevinçli, G. Cuniberti, J. Appl. Phys. 117, 074308 (2014). [6] DN, Lokamani, A. Santana-Bonilla, A. Dianat, R. Gutierrez, G. Cuniberti, J. Phys. Chem. Lett. 6, 3950 (2015).