Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 54: Transport: Carbon Nanotubes

TT 54.7: Hauptvortrag

Mittwoch, 9. März 2016, 16:45–17:15, H22

Cooling a nanomechanical resonator by electron transport in hybrid devices. — •Gianluca Rastelli, Pascal Stadler, and Wolfgang Belzig — Universität Konstanz, Germany

A still open challenge in nanoelectromechanical systems is the achievement of active cooling using purely electron transport in devices fabricated with bottom-up techniques as, for instance, carbon nanotube quantum dots suspended between two electric nano-contacts. Owing to the interaction between the electrons and the flexural mechanical modes, the electron transport results inelastic. The vibration assisted tunneling processes give rise to a mechanical damping and, for an applied bias-voltage, to a steady non-equilibrium phonon occupation of the resonator. I will discuss these effects for: (i) spin-polarised current between two ferromagnets [1,2] and (ii) sub-gap Andreev current between a superconductor and normal metal [3]. I will show that ground state cooling of the resonator can be achieved for realistic parameters of the system. I will also discuss the signatures of the non-equilibrium state of the resonator in the current-voltage characteristic.

[1] P. Stadler, W. Belzig, and G. Rastelli, PRL 113, 047201 (2014).

[2] P. Stadler, W. Belzig, and G. Rastelli, PRB 91, 085432 (2015).

[3] P. Stadler, W. Belzig, and G. Rastelli, arXiv:1511.04858.