[13a-A501-1~8] 10.3 Spin devices, magnetic memories and storages

▲ [13a-A501-8] Nanotesla-field detectivity with hysteresis-free magnetic tunnel junctions

〇(P)Mahmoud Rasly Eldesouky¹, Tomoya Nakatani¹ (1.NIMS)

Keywords:Magnetic field sensor, tunnel magnetoresistance, 1/f noise

On the requirements of low-noise magnetic field sensors based on magnetic tunnel junctions (MTJs), a hysteresis-free transfer curve is needed over a small-linear operating range. In this study, we have fabricated hysteresis-free MTJs by incorporation of an amorphous layer of CoFeBTa (CFBT) ferromagnetically coupled with CoFeB layer in top-pinned MTJs. Furthermore, we systematically investigated the CFBT thickness (t_CFBT) dependence of noise voltage. All fabricated MTJs showed 1/f noise behaviors with a strong magnetic-field dependence. As a normal behavior, the noise voltage in our MTJs increased as the bias voltage across junctions increased. Last, we found that a detectivity as low as 4 nT/Hz^0.5 is obtained for the MTJ sensor having t_CFBT = 20 nm. Nevertheless, detectivity increased as t_CFBT increased.