Abstract
Understanding how the orbital motion of electrons is coupled to the spin degree of freedom in nanoscale systems is central for applications in spin-based electronics and quantum computation. Here we demonstrate such spin–orbit coupling in a carbon-nanotube quantum dot in the general multielectron regime and in the presence of finite disorder. Also, we find a systematic dependence of the spin–orbit coupling on the electron occupation of the quantum dot. Such a dependence has not been seen in any other system and follows from the curvature-induced spin–orbit-split Dirac spectrum of the underlying graphene lattice. Our findings suggest that the spin–orbit coupling is a general property of carbon-nanotube quantum dots, which should provide a unique platform for the study of spin–orbit effects and their applications.
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Acknowledgements
We thank P. E. Lindelof, J. Mygind, H. I. Jørgensen, C. M. Marcus and F. Kuemmeth for discussions and experimental support. T.S.J. acknowledges the Carlsberg Foundation and Lundbeck Foundation for financial support. K.G-R., K.F. and J.N. acknowledge The Danish Research Council and University of Copenhagen Center of Excellence.
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T.S.J. and K.G-R. made the measurements, analysed the data and wrote the paper. T.S.J. designed the rotating sample stage. K.G-R. made the sample. K.M., T.F. and J.N. participated in discussions and writing the paper. J.P. and K.F. developed the theory and guided the experiment.
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Jespersen, T., Grove-Rasmussen, K., Paaske, J. et al. Gate-dependent spin–orbit coupling in multielectron carbon nanotubes. Nature Phys 7, 348–353 (2011). https://doi.org/10.1038/nphys1880
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DOI: https://doi.org/10.1038/nphys1880
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