Observation of large h/2e oscillations in semiconductor antidot lattices.

Abstract

We report the observation of large-amplitude oscillations in the magnetoresistance of a two-dimensional electron gas in a GaAs-${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As heterostructure with an artificially imposed antidot lattice potential. The period of the oscillations is about h/2e as a function of the magnetic flux threading through the unit cell of the antidot lattice. The oscillations are definitely visible in the antidot array with a hexagonal lattice configuration, the amplitude reaching 20% of the sample resistance, but almost invisible with a square lattice configuration. We believe that the hexagonal lattice potential is suitable for electrons to return to their starting points and to contribute to coherent backscattering. We also show the oscillations cannot be described by the theory for the diffusive regime estalished by Al'tshuler, Aronov, and Spivak.