Transport in ultra-narrow quantum well wires

Abstract

We have fabricated the narrowest conducting channels reported to date using hihg mobility GaAs/AlGaAs heterojunction material. In our narrowest wires at low temperatures and for small magnetic fields, where the lD subband splitting exceed both κ BT and h ̵ ω C , we observe striking departures from the 2D Hall effect. An unexpected Hall plateau at low magnetic field is observed which systematically moves to higher field and higher Hall resistance, R H, as the wire width is decreased. In samples having widths less than ≈ 200 nm, this is acompanied by a precipitous, complete suppression of R H within a region about zero field. We believe these to be unambiguous manifestations of one-dimensional electrical transport; they appear to provide a direct measure of the number of quantum conduction channels that participate [1].