Geometric resonances in the magnetoresistance of hexagonal lateral superlattices

TL;DR

This study investigates magnetoresistance oscillations in hexagonal lateral superlattices, revealing geometric resonances and miniband formation that could lead to realizing massless Dirac fermions in semiconductor 2DEGs.

Contribution

It demonstrates the observation of geometric resonances and open orbits in hexagonal superlattices, advancing the understanding of miniband formation in such structures.

Findings

Identification of three types of oscillations in magnetoresistance.

Detection of two characteristic periodicities in the lattice.

Observation of miniband formation indicating potential for Dirac fermions.

Abstract

We have measured magnetoresistance of hexagonal lateral superlattices. We observe three types of oscillations engendered by periodic potential modulation having hexagonal-lattice symmetry: amplitude modulation of the Shubnikov-de Haas oscillations, commensurability oscillations, and the geometric resonances of open orbits generated by Bragg reflections. The latter two reveal the presence of two characteristic periodicities, sqrt{3} a / 2 and a / 2, inherent in a hexagonal lattice with the lattice constant a. The formation of the hexagonal-superlattice minibands manifested by the observation of open orbits marks the first step toward realizing massless Dirac fermions in semiconductor 2DEGs.