  The widely reported magnetoresistance oscillations in LaAlO3/SrTiO3
heterostructures have invariably been attributed to the Shubnikov-de Haas (SdH)
effect, despite a pronounced inconsistency with low-field Hall resistance
measurements. Here we report SdH-like resistance oscillations in quasi-1D
electron waveguides created at the LaAlO3/SrTiO3 interface by conductive atomic
force microscopy lithography. These oscillations can be directly attributed to
magnetic depopulation of magnetoelectric subbands. Our results suggest that the
SdH oscillations in 2D SrTiO3-based systems may originate from naturally
forming quasi-1D channels.
