Macro-spin Modeling and Experimental Study of Spin-orbit Torque Biased Magnetic Sensors

摘要

We reported a systematic study of spin-orbit torque biased magnetic sensorsbased on NiFe/Pt bilayers through both macro-spin modeling and experiments. Thesimulation results show that it is possible to achieve a linear sensor with adynamic range of 0.1 - 10 Oe, power consumption of 1uW - 1 mW, and sensitivityof 0.1-0.5 Ohm/Oe. These characteristics can be controlled by varying thesensor dimension and current density in the Pt layer. The latter is in therange of 1 x 10^5 - 10^7 A/cm^2. Experimental results of fabricated sensorswith selected sizes agree well with the simulation results. For a Wheatstonebridge sensor comprising of four sensing elements, a sensitivity up to 0.548Ohm/Oe, linearity error below 6%, and detectivity of about 2.8 nT/Sqrt(Hz) wereobtained. The simple structure and ultrathin thickness greatly facilitate theintegration of these sensors for on-chip applications. As a proof-of-conceptexperiment, we demonstrate its application in detection of current flowing inan on-chip Cu wire.