III-V Ferromagnetic/Nonmagnetic Semiconductor Magnetodiodes for Use in Magnetic Field Sensors, Gaussmeters, and Other Magnetoresistive Devices (25014)
A novel "spintronic" magnetodiode based on a III-V ferromagnetic semiconductor and a III-V nonmagnetic semiconductor heterojunction has been created by Northwestern researchers. The diodes exhibit a large junction magnetoresistance that is linearly dependent on the applied magnetic field at room temperature, offering potential for new magnetic field sensor, gaussmeter, or other magnetoresistive devices.
ADVANTAGES: A new magnetodiode that can be integrated into present day semiconductor structures, enabling magnetic imaging or interface with optoelectronic devices, while operating linearly in high fields. The magnetodiodes are sensitive to both longitudinal and transverse fields in contrast to current magnetodevices. The devices exhibit lower power consumption than existing silicon magnetodiodes.
SUMMARY: Magnetic sensors are employed in a range of applications, including geophysical, automotive, biomedical measurement and control equipment. Recent advances in spintronic physics provide the basis for construction of new semiconductor magnetodiodes that overcome several limitations of the prior art. Thus fabrication of an epitaxial p-(In,Mn)As/n-InAs heterojunction, formed via metal-organic vapor phase epitaxy, enable construction of a novel magnetodiode (Figure 1). The magnetoresistance of the junctions measured as a function of forward bias and applied magnetic field is linear at room temperature (295 K) from 1.5 to 9 Tesla and potentially higher fields (Figure 2). At cryogenic temperatures (78 K), the magnetoresistance is linear from 0.1 to 9 Tesla. The difference between the longitudinal and transverse magnetoresistance is only 26% and 30% at 295 K and 78 K respectively, and provides a single device capable of sensing fields in both directions.
Steven May and Bruce Wessels
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