Spin Effects in Quantum Transport in Carbon Nanotubes
Zusammenfassung der Projektergebnisse
We have studied the scattering spectra of metallic single walled carbon-nanotubes containing structural defects as single- and di-vacancies as well as tube ends. The analysis was based on the local density of states associated with the quasi-boundstates between successive defects or in a finite size tube. In our model the defects, characterized by a dimension of the order of the carbon-carbon distance in the graphene lattice, are playing a key role. Indeed, they break the translational invariance and induce signals also in the umklapp scattering channels. These kind of processes are fully accounted for in our analytical model. We have compared our theoretical findings with the results of experiments realized on metallic nanotubes in which structural defects were created by ion bombardment or voltage pulses in the tip of a scanning tunneling microscope. The experimental Fourier analysis of the local density of states is in agreement with the one obtained from our theoretical model. We have explained some of the features observed in the experiments by employing an atomistic model in which we fully account for the realization of the defects in the lattice structure of the nanotube. We have also studied the change of the spectral properties of single layer graphene and graphene nano ribbons due to the presence of spin-orbit interaction. For the case of a one-dimensional modulation of intrinsic and extrinsic spin-orbit interactions we have predicted the emergence of spin polarized bands. In general, we observed a different group velocity for the two spin species. Finally, we have investigated the spectral properties of an armchair graphene nano ribbon. Here, we have imposed the boundary conditions on the tight binding Hamiltonians for bulk graphene with Rashba spin-orbit interaction by means of a sine transform and studied the influence of this interaction on the spectra and the spin polarization in detail.
Projektbezogene Publikationen (Auswahl)
- Defect-Induced Multicomponent Electron Scattering in Single-Walled Carbon Nanotubes. Phys. Rev. B 83, 165439 (2011)
D. Bercioux, G. Buchs, H. Grabert, and O. Gröning
- Dirac-Weyl electrons in a periodic spin-orbit potential. EPL 96, 27006 (2011)
L. Lenz and D. Bercioux
- Pseudo-spin-dependent scattering in carbon nanotubes. Phys. Rev. B 84, 115126 (2011)
L. Mayrhofer and D. Bercioux
- Pseudo-spin filter in metallic single-walled carbon nanotubes. Nano/Micro Engineered and Molecular Systems (NEMS), 2012, 7th IEEE International Conference.
D. Bercioux and L. Mayrhofer
- Rashba spin-orbit interaction in graphene armchair nanoribbons. Eur. Phys. J. B B 86, 502 (2013)
L. Lenz, D. F. Urban, and D. Bercioux
(Siehe online unter https://doi.org/10.1140/epjb/e2013-40760-4)
