Vertical cavity laser combined with a magnetic tunnel junction for optical sensing of magnetic fields

Summary form only given. Sensing magnetic fields "wirelessly" is of wide interest, from geological sensing to high-speed readout of magnetic storage media. We demonstrate a chipscale magneto-optoelectronic device, composed of a GaAs QW VCSEL and magnetic tunnel junction (MTJ). The integration of the two thin film epitaxial components creates a hybrid device where resistance changes in the tunnel junction in an external magnetic field are translated to changes in the intensity of the light emanating from the VCSEL source. The MTJs show promise for both magnetic sensing and in non-volatile random access memory applications. In an MTJ, a large room-temperature magnetoresistance is achieved in layered structures composed of two ferromagnetic (FM) layers with different coercivities separated by a thin aluminum oxide tunnel barrier. Fractional resistance changes reaching /spl Delta/R/R /spl sim/ 0.5 have been recently obtained in NiFeCo-based MTJs, for magnetic fields of the order of 100 Oe.