We investigate the longitudinal resistance of a semiconductor near-surface two-dimensional electron gas (2DEG) subjected to a magnetic barrier induced by the stray field from a single sub-micron ferromagnetic line on the surface of the device. The amplitude of the magnetic barrier is controlled by the application of an external magnetic field in the plane of the 2DEG. We show that this type of magnetoresistance can be used to deduce properties of the ferromagnetic line, so that our hybrid ferromagnet-semiconductor structure acts as a nanomagnetometer.

We present measurements on hybrid ferromagnetic/semiconductor devices. Single, submicron ferromagnetic structures have been fabricated directly onto the surface of a semiconductor, which incorporates a near-surface two-dimensional electron gas (2DEG). The induced Hall resistance and magnetoresistance of the 2DEG are used to measure the magnetic properties of the stripes directly. The relative merits of these two techniques are compared using a device geometry in which both types of measurement can be made simultaneously.

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