Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 103: Transport: Poster Session

TT 103.31: Poster

Donnerstag, 19. März 2015, 15:00–18:00, Poster B

The two classes of low energy spectra in finite carbon nanotubes — •Magdalena Marganska¹, Piotr Chudzinski^1,2, and Milena Grifoni¹ — ¹Institute for Theoretical Physics, Regensburg University, 93 053 Regensburg, Germany — ²Institute for Theoretical Physics, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands

Electrons in carbon nanotubes (CNTs) possess spin and orbital degrees of freedom. The latter is inherited from the bipartite graphene lattice with two inequivalent Dirac points. The electronic spectra obtained in several transport experiments on CNT quantum dots in parallel magnetic field often show an anticrossing of spectral lines assigned to the opposite Dirac valleys. So far this valley mixing has been attributed to the disorder, with impurity induced scattering with large momentum transfer. We show that this effect can arise also in ultraclean armchair-like CNTs, where it is caused solely by the presence of the boundaries. In zigzag-like CNTs it does not occur due to the angular momentum conservation - there the two valleys indeed correspond to different values of orbital angular momentum. In the armchair-like CNTs the orbital angular momentum in both valleys is zero and the degeneracy between valley states is removed. The magnitude of the level splitting depends in a non-monotonous way on the energy of the levels involved.