Home > News > Coupling of spin and orbital motion of electrons in carbon nanotubes
March 27th, 2008
Coupling of spin and orbital motion of electrons in carbon nanotubes
Abstract:
Electrons in atoms possess both spin and orbital degrees of freedom. In non-relativistic quantum mechanics, these are independent, resulting in large degeneracies in atomic spectra. However, relativistic effects couple the spin and orbital motion, leading to the well-known fine structure in their spectra. The electronic states in defect-free carbon nanotubes are widely believed to be four-fold degenerate1, 2, 3, 4, 5, 6, 7, 8, 9, 10, owing to independent spin and orbital symmetries, and also to possess electron-hole symmetry11. Here we report measurements demonstrating that in clean nanotubes the spin and orbital motion of electrons are coupled, thereby breaking all of these symmetries. This spin-orbit coupling is directly observed as a splitting of the four-fold degeneracy of a single electron in ultra-clean quantum dots. The coupling favours parallel alignment of the orbital and spin magnetic moments for electrons and antiparallel alignment for holes. Our measurements are consistent with recent theories12, 13 that predict the existence of spin-orbit coupling in curved graphene and describe it as a spin-dependent topological phase in nanotubes. Our findings have important implications for spin-based applications in carbon-based systems, entailing new design principles for the realization of quantum bits (qubits) in nanotubes and providing a mechanism for all-electrical control of spins14 in nanotubes.
Source:
nature.com
Bookmark:
News and information
How do cold ions slide May 24th, 2013
Heinrich Rohrer dies at 79; a father of nanotechnology: With IBM colleague Gerd Binnig, Rohrer invented the scanning tunneling microscope, which can show individual atoms on a surface and move them around May 23rd, 2013
Gold nanocrystal vibration captured on billion-frames-per-second film May 23rd, 2013
Glowing Plant Releases Maker Kit, Enabling Anyone to Make a Glowing Plant at Home: Glowing Plant seeks funds via crowdfunding and raises almost $400,000 May 23rd, 2013
Spintronics
Whirlpools on the Nanoscale Could Multiply Magnetic Memory: At the Advanced Light Source, Berkeley Lab scientists join an international team to control spin orientation in magnetic nanodisks May 22nd, 2013
New magnetic graphene may revolutionise electronics May 11th, 2013
Flawed Diamonds Promise Sensory Perfection: Berkeley Lab researchers and their colleagues extend electron spin in diamond for incredibly tiny magnetic detectors May 10th, 2013
New magnetic graphene may revolutionize electronics May 10th, 2013
Quantum Computing
Harris & Harris Group Notes the Sale of a Second D-Wave Quantum Computer May 16th, 2013
Cold atoms for quantum technology May 12th, 2013
Flawed Diamonds Promise Sensory Perfection: Berkeley Lab researchers and their colleagues extend electron spin in diamond for incredibly tiny magnetic detectors May 10th, 2013
New magnetic graphene may revolutionize electronics May 10th, 2013
Discoveries
How do cold ions slide May 24th, 2013
Gold nanocrystal vibration captured on billion-frames-per-second film May 23rd, 2013
Whirlpools on the Nanoscale Could Multiply Magnetic Memory: At the Advanced Light Source, Berkeley Lab scientists join an international team to control spin orientation in magnetic nanodisks May 22nd, 2013
Bacterial spare parts filter antibiotic residue from groundwater May 22nd, 2013
Announcements
How do cold ions slide May 24th, 2013
Heinrich Rohrer dies at 79; a father of nanotechnology: With IBM colleague Gerd Binnig, Rohrer invented the scanning tunneling microscope, which can show individual atoms on a surface and move them around May 23rd, 2013
Gold nanocrystal vibration captured on billion-frames-per-second film May 23rd, 2013
Glowing Plant Releases Maker Kit, Enabling Anyone to Make a Glowing Plant at Home: Glowing Plant seeks funds via crowdfunding and raises almost $400,000 May 23rd, 2013
Quantum nanoscience
Competition in the Quantum World May 20th, 2013
Scientists capture first direct proof of Hofstadter butterfly effect May 17th, 2013
New principle may help explain why nature is quantum May 15th, 2013
Flawed Diamonds Promise Sensory Perfection: Berkeley Lab researchers and their colleagues extend electron spin in diamond for incredibly tiny magnetic detectors May 10th, 2013