Reduction of low frequency magnetic noise by voltage-induced magnetic anisotropy modulation in tunneling magnetoresistance sensors

Abstract

We demonstrate the reduction and control of magnetic noise by voltage-induced perpendicular anisotropy modulation in CoFeB/MgO/CoFeB sensors. The noise decreases with the increase of the perpendicular anisotropy energy induced by the bias voltage polarity reversal. The bias reversal between −1 and +1 V results in a reduction of the normalized 1/f magnetic noise parameters by a factor of 7.3 and the thermal magnetic noise by a factor of 6.8. In the state of the highest field sensitivity, the lowest normalized 1/f magnetic noise parameter reaches 6.45 × 10−14 μm3T. The results indicate that voltage-induced anisotropy modulation can be used to control and suppress magnetization fluctuations in the sensing layer and thus, significantly reduce the magnetic noise.