Electric-field controlled spin reversal in a quantum dot with ferromagnetic contacts
| dc.creator | Hauptmann, J. R. | |
| dc.creator | Paaske, J. | |
| dc.creator | Lindelof, P. E. | |
| dc.date | 2007-11-02 | |
| dc.date.accessioned | 2026-07-07T10:11:07Z | |
| dc.date.available | 2026-07-07T10:11:07Z | |
| dc.description | Manipulation of the spin-states of a quantum dot by purely electrical means is a highly desirable property of fundamental importance for the development of spintronic devices such as spin-filters, spin-transistors and single-spin memory as well as for solid-state qubits. An electrically gated quantum dot in the Coulomb blockade regime can be tuned to hold a single unpaired spin-1/2, which is routinely spin-polarized by an applied magnetic field. Using ferromagnetic electrodes, however, the properties of the quantum dot become directly spin-dependent and it has been demonstrated that the ferromagnetic electrodes induce a local exchange-field which polarizes the localized spin in the absence of any external fields. Here we report on the experimental realization of this tunneling-induced spin-splitting in a carbon nanotube quantum dot coupled to ferromagnetic nickel-electrodes. We study the intermediate coupling regime in which single-electron states remain well defined, but with sufficiently good tunnel-contacts to give rise to a sizable exchange-field. Since charge transport in this regime is dominated by the Kondo-effect, we can utilize this sharp many-body resonance to read off the local spin-polarization from the measured bias-spectroscopy. We show that the exchange-field can be compensated by an external magnetic field, thus restoring a zero-bias Kondo-resonance, and we demonstrate that the exchange-field itself, and hence the local spin-polarization, can be tuned and reversed merely by tuning the gate-voltage. This demonstrates a very direct electrical control over the spin-state of a quantum dot which, in contrast to an applied magnetic field, allows for rapid spin-reversal with a very localized addressing. | |
| dc.description | 19 pages, 11 figures | |
| dc.identifier | https://arxiv.org/abs/0711.0320 | |
| dc.identifier | http://arxiv.org/abs/0711.0320 | |
| dc.identifier | Nature Physics 4, 373 - 376 (01 May 2008) | |
| dc.identifier | doi:10.1038/nphys931 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/171767 | |
| dc.subject | Mesoscale and Nanoscale Physics | |
| dc.subject | Strongly Correlated Electrons | |
| dc.title | Electric-field controlled spin reversal in a quantum dot with ferromagnetic contacts | |
| dc.type | text |