Superconductivity-enhanced bias spectroscopy in carbon nanotube quantum dots

K. Grove-Rasmussen; H. I. Jørgensen; B. M. Andersen; J. Paaske; T. S. Jespersen; J. Nygård; K. Flensberg; P. E. Lindelof

doi:10.1103/PhysRevB.79.134518

Superconductivity-enhanced bias spectroscopy in carbon nanotube quantum dots

K. Grove-Rasmussen, H. I. Jørgensen, B. M. Andersen, J. Paaske, T. S. Jespersen, J. Nygård, K. Flensberg, P. E. Lindelof

DOI 10.1103/PhysRevB.79.134518 · Physical Review B

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Abstract

We study low-temperature transport through carbon nanotube quantum dots in the Coulomb blockade regime coupled to niobium-based superconducting leads. We observe pronounced conductance peaks at finite source-drain bias, which we ascribe to elastic and inelastic cotunneling processes enhanced by the coherence peaks in the density of states of the superconducting leads. The inelastic cotunneling thresholds display a marked dependence on gate voltage caused by different tunneling renormalizations of the two subbands in the nanotube. Finally, we discuss the gate-dependent subgap structure observed in a strongly coupled device with odd electron occupation.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Nb Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	9	Pressure not reported	unknown
NbO Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.4	Pressure not reported	unknown