Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 11: Majorana Physics

TT 11.4: Hauptvortrag

Montag, 1. April 2019, 15:45–16:15, H4

Majorana states in carbon nanotubes — •Magdalena Marganska1, Lars Milz1, Wataru Izumida2, Christoph Strunk3, and Milena Grifoni11Institute for Theoretical Physics, University of Regensburg, 93 053 Regensburg, Germany — 2Department of Physics, Tohoku University, Sendai 980 8578, Japan — 3Institute for Experimental and Applied Physics, University of Regensburg, 93 053 Regensburg, Germany

One of the two most popular schemes for the realization of Majorana fermions uses proximitized semiconducting nanowires with spin-orbit coupling. With proper combination of magnetic field and gate voltage they can be driven into a topological phase, hosting zero energy Majorana bound states (MBS). Carbon nanotubes have similar properties and can be used in the same setup. They are however a hundred times thinner than the nanowires, which makes them truly one-dimensional systems, with only one relevant transverse mode for spin and valley degrees of freedom. Further, this allows us to perform a full microscopic tight-binding numerical simulation. Its results then serve as the reference for the construction of effective models in the reciprocal space.

In agreement with our numerics, the topological phase diagram predicts the presence of Majorana states at magnetic fields and chemical potentials which are encouraging for the planned experiments. The MBS themselves and their spin canting angle are revealed as complex entities, with a helical spatial profile made up from contributions from six different regions in the reciprocal space. This influences the coupling of the MBS to the outside world.

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