摘要：Large changes in the electrical resistance induced by the application of a small magnetic field are potentially useful for device-applications. Such Giant Magneto-Resistance (GMR) effects also provide new insights into the physical phenomena involved in the associated electronic transport. This study examines a “bell-shape” negative GMR that grows in magnitude with decreasing temperatures in mm -wide devices fabricated from the high-mobility GaAs/AlGaAs 2-Dimensional Electron System (2DES). Experiments show that the span of this magnetoresistance on the magnetic-field-axis increases with decreasing device width, W , while there is no concurrent Hall resistance, Rxy , correction. A multi-conduction model, including negative diagonal-conductivity, and non-vanishing off-diagonal conductivity, reproduces experimental observations. The results suggest that a size effect in the mm -wide 2DES with mm -scale electron mean-free-paths is responsible for the observed “non-ohmic” size-dependent negative GMR.
