Magnetic field sensing characteristics of MgO based tunneling magnetoresistance devices with Co40Fe40B20 and Co60Fe20B20 electrodes

We developed spin valve tunneling magnetoresistance devices based on MgO barrier and two compositions of CoFeB electrodes capable of sensing magnetic field in tunable ranges with high sensitivity and low nonlinearity. The tunable field ranges are due to varying strength of perpendicular anisotropy in a sensing electrode induced by changing its thickness. The sensing field ranges span from ±0.1 mT to ±100 mT. In the narrowest field range devices showed sensitivity up to 91%/mT and nonlinearity below 1.5% of full scale and in the widest field range sensitivity up to 0.076%/mT and nonlinearity below 2% of full scale. The sensing characteristics and their dependence on the electrode thickness suggest that these device structures are useful for design low to medium magnetic field sensors.