title: Large spin-orbit coupling in carbon nanotubes.
abstract: It has recently been recognised that the strong spin-orbit interaction present in solids can lead to new phenomena, such as materials with non-trivial topological order. Although the atomic spin-orbit coupling in carbon is weak, the spin-orbit coupling in carbon nanotubes can be significant due to their curved surface. Previous works have reported spin-orbit couplings in reasonable agreement with theory, and this coupling strength has formed the basis of a large number of theoretical proposals. Here we report a spin-orbit coupling in three carbon nanotube devices that is an order of magnitude larger than previously measured. We find a zero-field spin splitting of up to 3.4 meV, corresponding to a built-in effective magnetic field of 29 T aligned along the nanotube axis. Although the origin of the large spin-orbit coupling is not explained by existing theories, its strength is promising for applications of the spin-orbit interaction in carbon nanotubes devices.
authors.affiliation: Kavli Institute of NanoScience, Delft University of Technology, PO Box 5046, Delft 2600GA, The Netherlands. g.a.steele@tudelft.nl
authors.forename: G A
authors.initials: GA
authors.lastname: Steele
authors.forename: F
authors.initials: F
authors.lastname: Pei
authors.forename: E A
authors.initials: EA
authors.lastname: Laird
authors.forename: J M
authors.initials: JM
authors.lastname: Jol
authors.forename: H B
authors.initials: HB
authors.lastname: Meerwaldt
authors.forename: L P
authors.initials: LP
authors.lastname: Kouwenhoven