RESEARCH IN THE NEWS: THERE`S (STILL) MORE TO CARBON NANOTUBES!

In the March 24 issue of Nature, researchers from the Kavli Institute of Nanoscience show that the fundamental properties of carbon nanotubes are far from being fully explored.

The authors, a collaboration between the Quantum Transport and Molecular Biophysics groups in Delft, have demonstrated that carbon nanotubes possess an orbital magnetic moment which can behave as the spin magnetic moment. Therefore this orbital magnetic moment acts as a pseudo-spin. Pablo Jarillo-Herrero, Jing Kong, Herre van der Zant, Cees Dekker, Leo Kouwenhoven and Silvano De Franceschi have measured a fundamental spin-related phenomenon, called the Kondo effect, in carbon nanotubes, but using the orbital pseudo-spin instead of the electron spin.

In the Kondo effect, the conductance through a quantum dot (or artificial atom) is largely enhanced at low temperatures due spin-spin interactions. What Jarillo-Herrero and collaborators have shown is that this is also possible for spin-less electrons (or equally, for spin polarized electrons), by means of pseudospin-pseudospin interactions. This work represents also a proof of principles that carbon nanotubes could potentially be used as high conductance spin filters, one of the holy grails of the rapidly developing field of spintronics.

The full paper can be found in Nature 434, pages 484-488 (24 March 2005)