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(a) Illustration of a three-terminal MTJ with a Hall cross geometry. The black (blue) ‘up’ and red (yellow) ‘down’ arrows indicate the equilibrium magnetization states of the bottom (top) FeCoB layers. (b) Scanning electron microscopy image of a 1 μm diameter MTJ dot on top of a 1.3 μm wide Ta electrode with a schematic representation of the electrical measurement setup. , , and represent the two terminals for the Hall voltage and MTJ voltage measurements, respectively.
(a) TMR as a function of the perpendicular magnetic field for a 1 μm dot diameter. The black and red curves show, respectively, a major and a minor loop. (b) TMR as a function of current pulse amplitude I p injected in the Ta electrode using 50 ns long pulses under an in-plane magnetic field H l = −0.4 kOe. The arrows show the sweep direction of I p.
(a) Schematic of the pulse sequence. (b) The AHE resistance (proportional to the M z component of the bottom FeCoB layer) and (c) TMR measured after the injection of positive (black squares) and negative (red circles) current pulses of amplitude I p = 20 mA and 50 ns long under H l = −0.4 kOe.
(a) The AHE resistance and (b) TMR as a function of H l measured after the injection of positive (black squares) and negative current pulses (red circles) of amplitude I p = 20 mA and a length of 50 ns. The MTJ dot diameter is 1 μm. H l is swept from negative to positive magnetic fields.
(a) I P -H l switching diagram constructed from the measurement of the TMR signal for a 1 μm diameter MTJ (50 ns long pulses). Region I: current assisted magnetization reversal. The open black up-triangles and the dotted line indicate the coercive field of the bottom and top FeCoB layers, respectively. Region II: low TMR signal (parallel alignment). Region III: Current-induced magnetization switching. The red squares and the blue circles indicate the maximum field and minimum field at which current induced magnetization switching of the bottom layer is observed. and indicate the parallel state where both FeCoB magnetizations are oriented upward and downward, respectively. (b) Dependence of the critical current j c on the inverse pulse width ( p). The black line is a guide for the eyes.
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