ANISOTROPIC MAGNETOTRANSPORT IN AN ANTIWIRE ARRAY INSERTED IN A GAAS HETEROSTRUCTURE

An array of antiwires is prepared in GaAs/AlGaAs heterostructures by using the tilted superlattice approach. A regular two-dimensional electron gas (2DEG) is grown on a 2o off axis (100) substrate. Half a monolayer of AlAs is inserted close to the GaAs/AlGaAs interface ordering itself along the step edges. Therefore an antiwire array is formed which directly influences the envelope wavefunction of the two-dimensional electrons. Low temperature magnetotransport measurements with current flow parallel and perpendicular to the wires reveal a pronounced anisotropy in the magnetoresistance ρ{variant}xx of the carriers. The value of ρ{variant}xx⊥(B=0) for current flow perpendicular to the antiwires is larger than g9xx|. The anisotropy increases with increasing carrier density in agreement with the formation of Bloch bands due to the periodicity of the antiwire array. For high magnetic fields B>2T the minima of the Shubnikov-de Haas oscillations for ρ{variant}xx⊥ and ρ{variant}xx| occur at the same fields indicating the homogeneity of the 2DEG. For low magnetic fields B≈0.5T we observe a maximum in ρ{variant}xx⊥ while ρ{variant}xx| stays constant. The Hall resistances ρ{variant}xy⊥ and ρ{variant}xy| are indistinguishable from each other for all ranges of B and Ns. © 1991.