Open Access Te Herenga Waka-Victoria University of Wellington
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Magneto-tunnelling transport of chiral charge carriers

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posted on 2021-11-14, 08:41 authored by Pratley, Luke

We study magneto-tunnelling between two parallel two-dimensional electron gases theoretically, where the electrons have a pseudo-spin-½ degree of freedom that is coupled to their momentum. The two-dimensional electron gases focused on in this work are single layer graphene, bilayer graphene, and single layer molybdenum disulphide. The results are derived using a linear response theory formalism in the weak tunnelling regime, and it is assumed that the electron gases are at zero temperature, with no interactions or disorder. The linear magneto-tunnelling conductance characteristics for an applied in-plane and tilted magnetic field are found to strongly depend on the pseudo-spin structure of the tunnelling matrix and the pseudo-spin's dependence on momentum. For instance, resonances in the linear magneto-tunnelling conductance are sensitive to the pseudo-spin tunnel-coupling across the barrier and how the pseudo-spin eigenstates are coupled to momentum. We discuss how measurements of the magneto-tunnelling conductance can be applied as a spectroscopic tool. We explain how to measure the pseudo-spin tunnel-coupling through least squares parameter fitting of the magneto-tunnelling conductance. We show that the parameters are interdependent, one can use the interdependency to test the consistency between theory and experiment. It is expected that measurements of pseudo-spin tunnel-coupling will be a function of the lattice structure of the double layer system, which suggests these measurements can be used as a spectroscopic tool. Additionally, we investigate in-plane electric fields in single layer graphene to see if their effects can be observed in magneto-tunnelling transport. Then, we perturbatively include the effects of electron-electron interactions in single layer graphene, and find it should dampen the linear tunnelling conductance. We investigate tunnel-coupled , parallel , single layer and bilayer graphene systems. We find that using an in-plane magnetic field, one can generate a valley polarized tunnelling current. This method is unique because it does not require manipulation of the single and bilayer graphene samples through nano-structuring, coupling to electromagnetic fields, application of mechanical strain, or the presence of defects. In particular, the valley polarization is dependent on the pseudo-spin tunnel-coupling between the single and bilayer graphene systems, and the strength of an applied in-plane magnetic field. We explicitly show through analytic derivations how an understanding of linear magneto-tunnelling transport (zero bias limit) can be used to understand non-linear magneto-tunnelling transport (finite bias).


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Te Herenga Waka—Victoria University of Wellington

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Degree Grantor

Te Herenga Waka—Victoria University of Wellington

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Degree Name

Master of Science

ANZSRC Type Of Activity code

970102 Expanding Knowledge in the Physical Sciences

Victoria University of Wellington Item Type

Awarded Research Masters Thesis



Victoria University of Wellington School

School of Chemical and Physical Sciences


Zülicke, Ulrich