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TU Dresden » Faculty of Mechanical Science and Engineering » Institute for Materials Science » Chair of Materials Science and Nanotechnology

Friday, 11 November 2016
(at 13:00 in room 115, Hallwachsstr. 3)
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Intra- and inter-shell Kondo effect in carbon nanotubes

Prof. Stanislaw Lipinski

Institute of Molecular Physics, Polish Academy of Sciences, Poland

Spin and orbital degeneracies in carbon nanotubes can occur simultaneously leading to a highly symmetric Kondo state of SU(4) symmetry. The orbital degeneracy corresponds to clockwise and anticlockwise motion. The simultaneous screening of orbital and spin degrees of freedom is caused by tunneling processes causing spin, orbital pseudospin and spin-orbital fluctuations. More recent reports show that due to curvature induced spin-orbit coupling ( SOI) spin-orbital symmetry is broken in ultraclean tubes. SOI it is comparable with a typical Kondo scale in these systems. The question arises what effect does s-o coupling have on the SU(4) Kondo effect. We discuss various transport properties of carbon nanotube dots in the Kondo range examining the influence of magnetic field and intervalley mixing. A crossover between SU(4) Kondo state and SU(2) is analyzed. Within a shell, two SU(2) Kondo effects of different origins are possible, valley SU(2) Kondo effect at half filling and spin SU(2) Kondo for odd occupations. Additionally, inter-shell Kondo effects can arise at finite magnetic field due to level crossing between two different shells.

Announcement (pdf)

Brief Bio:

Lipinski has the full professor position at the Institute of Molecular Physics PAS. His main research topics are: 1) theory of magnetic alloys (magnons in disordered systems, magnetic solitons, modulated structures, short range magnetic order above Tc , superweak magnetism, magnetoelastic and magnetodistortive instabilities). 2) heavy fermion systems (coupling of charge, lattice and valence fluctuations, dynamic crystal field theory, magnetic fluctuations in HF systems). 3) transport in nanoscopic systems (strong correlation and interference effects in semiconducting quantum dots, graphene nanoribbons and carbon nanotubes).
Lipinski collaborates with several European groups. He spent several years working at RWTH Aachen, Institute Laue-Langevin Grenoble and Loughborough University. He published over sixty scientific papers and several book chapters.

Invited by G. Cuniberti

Within the nanoModSeminar

last modified: 2021.10.21 Thu
author: webadmin