Theoretical study on novel electronic properties in nanographite materials

TL;DR

This paper provides a theoretical analysis of novel electronic properties in nanographite, including magnetism, charge polarization, and interference patterns, using Hubbard models and electronic wave function analysis.

Contribution

It introduces new theoretical insights into magnetic and charge behaviors in nanographite, linking electronic structure to experimental observations.

Findings

Open shell electronic structure reduces magnetic moment with decreasing inter-graphene distance.

Charge-polarized states can emerge under static electric fields in graphene.

Oscillation periods of interference patterns decrease spatially, matching experimental STM data.

Abstract

Antiferromagnetism in stacked nanographite is investigated with using the Hubbard-type model. We find that the open shell electronic structure can be an origin of the decreasing magnetic moment with the decrease of the inter-graphene distance, as experiments on adsorption of molecules suggest. Next, possible charge-separated states are considered using the extended Hubbard model with nearest-neighbor interactions. The charge-polarized state could appear, when a static electric field is present in the graphene plane for example. Finally, superperiodic patterns with a long distance in a nanographene sheet observed by STM are discussed in terms of the interference of electronic wave functions with a static linear potential theoretically. In the analysis by the k-p model, the oscillation period decreases spatially in agreement with experiments.