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TT: Fachverband Tiefe Temperaturen

TT 10: Nanotubes and Nanoribbons

TT 10.1: Vortrag

Montag, 16. März 2020, 11:30–11:45, HSZ 204

Correlated or coherent - Kondo-like features in carbon nanotubes with transparent contacts — •Magdalena Margańska¹, Wei Yang², Carles Urgell², Sergio Lucio de Bonis², Milena Grifoni¹, and Adrian Bachtold² — ¹Institute for Theoretical Physics, University of Regensburg, 93053 Regensburg, Germany — ²ICFO - Institut De Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain

We report on electron transport measurements in high-quality carbon nanotube devices with a total transmission of about 1.5 e²/h. At high temperatures the linear conductance exhibits moderate oscillations as a function of the gate voltage around an average value of the order the quantum of conductance. Upon decreasing temperature, we observe an intriguing fourfold increase in the period of the oscillations accompanied by an enhancement in their amplitude. This temperature dependence is rather unusual. On the one hand, the high temperature oscillations are suggestive of charging effects in an open carbon nanotube quantum dot. On the other hand the low temperature transport characteristics is reminiscent of single-particle Fabry-Pérot interference in a carbon nanotube waveguide. We reconcile these observations by attributing the four-fold increase to the interplay of resonant tunneling, interaction and quantum fluctuations, leading to an SU(4) Kondo-like enhancement in open quantum dots systems. Our work provides a comprehensive phenomenology of transport in nanotubes when both interference and interaction are involved.