Control of vibrational states by spin-polarized transport in a carbon nanotube resonator

Anno: 2015

Autori: Stadler P., Belzig W., Rastelli G.

Affiliazione autori: Univ Konstanz, Fachbereich Phys, D-78457 Constance, Germany; Univ Konstanz, Fachbereich Phys, Zukunftskolleg, D-78457 Constance, Germany

Abstract: We study spin-dependent transport in a suspended carbon nanotube quantum dot in contact with two ferromagnetic leads and with the dot?s spin coupled to the flexural mechanical modes. The spin-vibration interaction induces spin-flip processes between the two energy levels of the dot. This interaction arises from the spin-orbit coupling or a magnetic field gradient. The inelastic vibration-assisted spin flips give rise to a mechanical damping and, for an applied bias voltage, to a steady nonequilibrium occupation of the harmonic oscillator. We analyze these effects as function of the energy-level separation of the dot and the magnetic polarization of the leads. Depending on the magnetic configuration and the bias-voltage polarity, we can strongly cool a single mode or pump energy into it. In the latter case, we find that within our approximation, the system approaches eventually a regime of mechanical instability. Furthermore, owing to the sensitivity of the electron transport to the spin orientation, we find signatures of the nanomechanical motion in the current-voltage characteristic. Hence, the vibrational state can be read out in transport measurements.


Volume: 91 (8)      Da Pagina: 085432  A:

Maggiori informazioni: This research was kindly supported by the EU FP7 Marie Curie Zukunftskolleg Incoming Fellowship Programme, University of Konstanz (Grant No. 291784) and by the DFG through the Collaborative Research Center SFB 767 and through the Project BE 3803/5.
Parole chiavi: quantum dots, quantum electromechanical systems, spin transport
DOI: 10.1103/PhysRevB.91.085432