The sensitivities of giant magnetoresistance (GMR) and planar Hall resistance (PHR) from different classes of magnetic multilayers were compared for biosensing applications. The magnetoresistance ratio (MR), exchange coupling field ($H_{\text{ex}}$), coercivity ($H_{\text{c}}$), interlayer coupling field ($H_{\text{int}}$), and magnetic sensitivity (MS) were measured, and in each sample, the thickness of the nonmagnetic Cu layer was varied to control magnetic exchange interactions and other magnetic characteristics to ensure that the MR and the PHR were more sensitive to the magnetic field. In each case, we found that the sensitivities of the MR and the PHR with respect to the magnetic field were greatly enhanced as the thickness of the Cu layer was increased, thus suggesting a way to engineer highly sensitive MR and PHV devices for use in biosensors.

Keywords: Giant magnetoresistance-spin valve (GMR-SV), Planar Hall voltage (PHV), Magnetic sensitivity (MS), Interlayer coupling field, Magnetoresistance ratio (MR)