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

Electronic eigen-states of a square graphene quantum dot(GQD) terminated byboth zigzag and armchair edges are derived in the theoretical framework ofDirac equation. We find that the Dirac equation can determine the eigen-energyspectrum of a GQD with high accuracy even if its size is reduced to a fewnanometers. More importantly, from the Dirac equation description we canreadily work out the number and energy gap of the conjugate surface states,which are intimately associated with the magnetic properties of the GQD. Byusing the Hartree-Fock mean field approach, we study the size dependence of themagnetic ordering formation in this square GQD. We find that there exists acritical size of the width between the two zigzag edges to indicate the onsetof the stable magnetic ordering. On the other hand, when such a width increasesfurther, the magnetic ground state energy of a charge neutral GQD tends to asaturated value. These results coincide with the previous results obtained fromthe first principle calculation. Then, based on the Dirac equation solutionabout the surface state, we establish a simple two-state model which canquantitatively explain the size dependence of the magnetic ordering in thesquare GQD.

Dirac equation description on the electronic states and magnetic properties of a square graphene quantum dot