We report on a colossal negative magnetoresistance (MR) in a GaAs/AlGaAs quantum well which, at low temperatures, is manifested by a drop of the resistivity by more than an order of magnitude at a magnetic field $B\approx 1$ kG. In contrast to MR effects discussed earlier, the MR reported here is not parabolic, even at small $B$, and persists to much higher in-plane magnetic fields and temperatures. Remarkably, the temperature dependence of the resistivity at $B\approx 1$ kG is linear over the entire temperature range studied (from 1 to 30 K) and appears to coincide with the high-temperature limit of the zero-field resistivity, hinting on the important role of acoustic phonons.

• Received 4 March 2014

DOI:https://doi.org/10.1103/PhysRevB.89.201301