Thomas Frederiksen: An electronic beam splitter realized with crossed graphene nanoribbons

T. Frederiksen(1,2), P. Brandimarte(3), M. Engelund(3), N. Papior(4), A. Garcia-Lekue(1,2), D. Sánchez-Portal(1,3) 1) Donostia International Physics Center (DIPC), Donostia-San Sebastian, Spain 2) Ikerbasque, Basque Foundation for Science, Bilbao, Spain 3) Centro de Fisica de Materiales CSIC-UPV/EHU, Donostia-San Sebastián, Spain 4) CNG, DTU Nanotech, Lyngby, Denmark  Graphene nanoribbons (GNRs) are promising components in future nanoelectronics. We have explored a prototype 4-terminal semiconducting device formed by two crossed armchair GNRs (AGNRs) [1] using state-of-the-art first-principles transport methods [2]. We analyze in detail the roles of intersection angle, stacking order, inter-GNR separation, and finite voltages on the transport characteristics. Interestingly, when the AGNRs intersect at 60 degrees, electrons injected from one terminal can be split into two outgoing waves with a tunable ratio around 50% and with negligible back-reflection. The split electron wave is found to propagate partly straight across the intersection region in one ribbon and partly in one direction of the other ribbon, i.e., in analogy of an optical beam splitter. Our simulations further identify realistic conditions for which this semiconducting device can act as a mechanically controllable electronic beam splitter with possible applications in carbon-based quantum electronic circuits and electron optics. [1] P. Brandimarte, M. Engelund, N. Papior, A. Garcia-Lekue, T. Frederiksen, D. Sánchez-Portal, J. Chem. Phys. 146, 092318 (2017). [2] N. Papior, N. Lorente, T. Frederiksen, A. García, and M. Brandbyge, Comput. Phys. Commun. 212, 8 (2017). Thomas Frederiksen is Ikerbasque Research Professor at the Donostia International Physics Center (DIPC) in Donostia-San Sebastian, Spain, since 2012. He obtained his PhD in 2007 from the Technical University of Denmark under the supervision of Prof. Mads Brandbyge and Prof. Antti-­Pekka Jauho. In 2008 he was awarded a 5-year Gipuzkoa Fellowship to carry out research at the DIPC and abroad. His research focuses on quantum transport theory, electronic structure methods, and simulation of nanostructures and interfaces.