Characterization of Nanomagnet Fringing Fields in Hybrid Semiconductor/Ferromagnetic Devices

We describe the fabrication of a hybrid nanomagneto-electronic device, consisting of a GaAs/AlGaAs quantum wire that is bridged by a ferromagnetic gate, and study the influence of the nanomagnet fringing fields on the quantum-wire magneto-resistance. The nonplanar gate shows clear single-domain structure in magnetic-force microscopy, and a simple magnetization behavior in an external magnetic field. This behavior is reflected as a hysteretic variation of the quantum-wire magneto-resistance, whose magnitude is found to be consistent with theoretical predictions for ballistic electron transport through a spatially varying magnetic field.