We report the observation of a new phenomenon of colossal magnetoresistance in a 40 nm wide GaAs quantum well in the presence of an external magnetic field applied parallel to the high-mobility 2D electron layer. In a strong magnetic field, the magnetoresistance is observed to increase by a factor of ~300 from 0 to 45T without the system undergoing any metal-insulator transition. We discuss how this colossal magnetoresistance effect cannot be attributed to the spin degree-of-freedom or localization physics, but most likely emanates from strong magneto-orbital coupling between the two-dimensional electron gas and the magnetic field. Our observation is consistent with a field-induced 2D-to-3D transition in the confined electronic system.
@article{arxiv.1003.5920,
title = {Colossal magnetoresistance in an ultra-clean weakly interacting 2D Fermi liquid},
author = {Xiaoqing Zhou and B. A. Piot and M. Bonin and L. W. Engel and S. Das Sarma and G. Gervais and L. N. Pfeiffer and K. W. West},
journal= {arXiv preprint arXiv:1003.5920},
year = {2015}
}