Magnetoresistance Based Nano-sensors

In the last few decades, magnetism coupled with nanotechnology has unlocked vast areas of research and thus nanomagnetism have elevated modern microelectronics several levels higher. Of late, magnetoresistance-based devices encompassing Giant magnetoresistance (GMR), Anisotropic magnetoresistance (AMR) and Tunneling magnetoresistance (TMR) have been used in the fabrication of nanosensors with metals, semiconductors and oxides nanoparticles. It is well known that Magnetoresistance is a phenomenon that relates the externally applied magnetic field to the resistance of the material. AMR effect is observed because of the change in resistivity in ferromagnetic materials with change in current direction and magnetization. GMR effect is seen in multilayers and granular structures due to antiferromagnetic exchange coupling between ferromagnetic and non-magnetic materials whereas the TMR effect relies on the tunneling effect in presence of external magnetic field. The resolution and range of the response of magnetoresistive sensors can be controlled and they have shown soundly high sensitivities, portability, low cost, rapid assay because of which it has been used extensively in sensing applications especially in clinical diagnostics and computer hard drives. In this study, we show the recent advancements in the field of magnetoresistance and their applications in sensing. The study has been performed to provide a broader outlook about the phenonmenon and their applications as different sensors.