Coulomb drag between quantum wires: Magnetic field effects and negative anomaly

We have measured the drag resistance R_D between parallel, split gate quantum wires fabricated on an n-GaAs/GaAs 2DEG heterostructure in magnetic fields B from zero up to the edge state regime. We find that a peak in R_D associated with the alignment of the Fermi wave vectors in the drive and drag wires at B = 0 vanishes in the edge state regime of the drag-wire conductance. This effect is attributed to suppressed backscattering. By contrast, when the conductance of both wires is appreciably below the first plateau, a peak in R_D which occurs for B = 0 is enhanced by an order of magnitude in the strong field. This behavior appears to emerge from the quasi-singular nature of the density of states at the bottom of a Landau band. Finally, for both zero and non-zero fields, we observe negative Coulomb drag when the drive-wire density is driven close to pinch off and it is high enough. The negative drag can be explained in terms of the response of a 1D Fermi liquid to a sliding Wigner crystal in the drive wire.