Nanosecond magnetic switching of ferromagnet-antiferromagnet bilayers in thermally assisted magnetic random access memory

The magnetic switching of the exchange biased storage layer in thermally assisted magnetic random access memory cells has been studied in the nanosecond time domain. Under reversed static external field, the magnetic tunnel junctions (MTJs) were subjected to current heating pulses long enough to heat the structure above the blocking temperature of the antiferromagnetic layer. The magnetic response of the storage layer was characterized by single-shot real-time measurement of MTJ resistance. The switching of the storage layer exhibits stochastic fluctuations. Nevertheless, using a heating current density of 4.7x10(6) A/cm(2) corresponding to a bias voltage of 1.8 V, the switching takes place in less than 4 ns under 5 mT. Interestingly, the probability of switching versus pulse duration exhibits characteristic periodic steps which are ascribed to a combined effect of the applied field and spin transfer produced by the heating current pulses.