2D–1D crossover behaviors in low–field magnetotransport

The 2D-1D crossover behavior has been investigated in narrow GaAs/AlGaAs heterostructures with a range of aspect ratio (a ratio of length to width of channel, L/W) of 2-240. In spite of the electron density constant as (3.9±0.3)xl0¹¹ cm^-2, a rapid change in the electron mobility arises around L/W=18. While the mobility keeps nearly constant for L/W <18, the exponential reduction has been experimentally clarified by an empirical equation of μ~[L/W]^-027 for L/W> 18. The 2D interaction parameter determined in the parabolic regime of negative magnetoresistance is ranging in (0.64±0.05) for L/W <18, but enhances up to 1.27 for L/W = 240 which is close to the calculated ID parameter. Similar crossover behaviors appear in changes of the asymmetric and aperiodic natures of Shubnikov-de Haas oscillation and its onset magnetic field.