Low frequency noise characterization of CoFeB/MgO/CoFeB MTJ based perpendicular field sensor

In a magnetic tunnel junction (MTJ) device, the potential barrier height of the barrier layer, in presence of a bias voltage or an external magnetic field, can be affected by defects present in the barrier layer or at the barrier layer/ferromagnetic (FM) layer interfaces of the device. The defects may have structural as well as magnetic origin. Fluctuations of such defects (with a time scale that corresponds to low frequency regime of <;10 kHz) can significantly change the tunnelling probability of conduction electrons through the insulating barrier layer leading to resistance fluctuations and hence affecting the device performance at that frequency range. Hence, considerable efforts have been made to understand the nature of the fluctuations and to find the ways to minimize it but, mostly have done for the MTJ devices that have parallel (or anti-parallel) configuration of the free and pinned layer magnetizations. Here, we are reporting low frequency electrical noise study of micron sized and elliptical shaped Co₄₀Fe₄₀B₂₀/MgO/ Co₂₀Fe₆₀B₂₀ based MTJ devices which have the reference and sensing layer magnetization directions along the out of plane and in plane directions, respectively designed for high sensitive perpendicular magnetic field sensor application.