Dresden 2014 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 80: Transport: Carbon nanotubes (organized by TT)

HL 80.5: Talk

Wednesday, April 2, 2014, 17:30–17:45, HSZ 304

Signatures of quanta of 1D collective modes in inelastic co- tunneling through a metallic carbon nanotube. — Daniel Steininger¹, •Piotr Chudzinski², Amit Kumar¹, Martin Gaim¹, Milena Grifoni², Andreas K. Hüttel¹, and Christoph Strunk¹ — ¹Institute for Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany — ²Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany

We report low temperature transport properties of an individual single wall carbon nanotube contacted to superconducting leads. Coulomb diamonds with sharp elastic and inelastic co-tunneling features at applied bias voltages of 2Δ/e and (2Δ+δ)/e (with the BCS gap Δ), respectively, are observed. Higher order transport processes generate subgap features at bias voltage Δ/e via the Andreev reflection process. In contrast to previously reported co-tunneling spectra [1], the elastic/in-elastic co-tunneling features we observe are horizontal lines on the bias-gate voltage plane (no bending effect) and do not display any effect related to even and odd electron occupancy of the quantum dot. The in-elastic part has a rich internal structure consisting of several equidistant sub peaks. We analyze various possibilities for the occurrence of such harmonic spectrum. Among these are vibrational excitations of the carbon lattice or the many body bosonic modes that are expected from the Tomonaga-Luttinger liquid description of single wall carbon nanotubes.
Phys. Rev. B 79, 134518