Abstract
The application of a small magnetic field either parallel or perpendicular to a low-density magnetic two-dimensional electron gas (2DEG) creates a striking positive magnetoresistance of up to 700%. This is a spin effect, caused by the suppression of spin-dependent hopping paths between localized states with on-site correlation. At higher fields, a spin-related delocalization is observed. In the perpendicular field geometry, orbital effects combine with this delocalization and lead to quantum phase transitions between the spin-polarized insulating state and the quantum Hall liquid.
- Received 13 May 1998
DOI:https://doi.org/10.1103/PhysRevB.58.R4238
©1998 American Physical Society