English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

For a massive quantum fermionic field, we investigate the vacuum expectationvalues (VEVs) of the charge and current densities induced by an externalmagnetic flux in a two-dimensional circular ring. Both the irreduciblerepresentations of the Clifford algebra are considered. On the ring edges thebag (infinite mass) boundary conditions are imposed for the field operator.This leads to the Casimir type effect on the vacuum characteristics. The radialcurrent vanishes. The charge and the azimuthal current are decomposed into theboundary-free and boundary-induced contributions. Both these contributions areodd periodic functions of the magnetic flux with the period equal to the fluxquantum. An important feature that distinguishes the VEVs of the charge andcurrent densities from the VEV of the energy density, is their finiteness onthe ring edges. The current density is equal to the charge density for theouter edge and has the opposite sign on the inner edge. The VEVs are peakednear the inner edge and, as functions of the field mass, exhibit quitedifferent features for two inequivalent representations of the Cliffordalgebra. We show that, unlike the VEVs in the boundary-free geometry, thevacuum charge and the current in the ring are continuous functions of themagnetic flux and vanish for half-odd integer values of the flux in units ofthe flux quantum. Combining the results for two irreducible representations, wealso investigate the induced charge and current in parity and time-reversalsymmetric models. The corresponding results are applied to graphene rings withthe electronic subsystem described in terms of the effective Dirac theory withthe energy gap. If the energy gaps for two valleys of the graphene hexagonallattice are the same, the charge densities corresponding to the separatevalleys cancel each other, whereas the azimuthal current is doubled.

Induced fermionic charge and current densities in two-dimensional rings