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Helical Level Structure of Dirac Potential Wells.

ABSTRACT: In graphene and other massless two-dimensional Dirac materials, Klein tunneling compromises electron confinement, and momentum-space contours can be assigned a Berry phase which is either zero or ?. Consequently, in such systems the energy spectrum of circular potential wells exhibits an interesting discontinuity as a function of magnetic field B: for a given angular momentum the ladder of eigen-resonances is split at an energy-dependent critical field B c. Here we show that introducing a mass term ? in the Hamiltonian bridges this discontinuity in such a way that states below B c are adiabatically connected to states above B c whose principal quantum number differs by unity depending on the sign of ?. In the B-? plane, the spectrum of these circular resonators resembles a spiral staircase, in which a particle prepared in the ?n, m? resonance state can be promoted to the ?n± 1, m? state by an adiabatic circuit of the Hamiltonian about B c, the sign depending on the direction of the circuit. We explain the phenomenon in terms of the evolving Berry phase of the orbit, which in such a circuit changes adiabatically by 2?.

SUBMITTER: Walkup D

PROVIDER: S-EPMC6604641 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Helical Level Structure of Dirac Potential Wells.

Walkup Daniel D Stroscio Joseph A JA

Physical review. B 20170101

In graphene and other massless two-dimensional Dirac materials, Klein tunneling compromises electron confinement, and momentum-space contours can be assigned a Berry phase which is either zero or π. Consequently, in such systems the energy spectrum of circular potential wells exhibits an interesting discontinuity as a function of magnetic field B: for a given angular momentum the ladder of eigen-resonances is split at an energy-dependent critical field B c. Here we show ...[more]

PMID: 31276077

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Helical Level Structure of Dirac Potential Wells.

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Helical Level Structure of Dirac Potential Wells.

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