Magnetic Sensitivity in Mesoscopic EMR Devices in I-V-I-V Configuration

Magnetic field sensors utilizing the extraordinary magnetoresistance effect (EMR) have been proposed for application in future magnetic recording applications. For a decade, Giant Magnetoresistance (GMR) sensor technology has scaled phenomenally well and has resulted in the successful demonstration of recording areal density greater than 230 Gbit/in
²
. However, as critical dimensions decrease below 50 nm, deleterious effects associated with thermal magnetic-noise and spin torque become increasingly difficult to avoid in GMR and related devices. EMR devices are hybrid distributed resistors comprised of a high mobility semiconductor in parallel and in contact with a low resistance metallic shunt. A magnetic field applied perpendicular to the wafer plane modulates the device resistance by selectively steering the current between the semiconductor and the shunt. Although this phenomenon is similar to the Hall Effect, modeling and experiments have suggested that the sensitivity is significantly greater than traditional Hall sensors. Additionally, no ferromagnetic materials are incorporated in EMR precluding vulnerability to magnetic noise sources.