Reversing Exchange Bias In Thermally Assisted Magnetic Random Access Memory Cell By Electric Current Heating Pulses

摘要

The temperature required to set the exchange bias of a ferro/antiferromagnetic (F/AF) storage bilayer as a function of the heating pulse width was studied on magnetic tunnel junctions (MTJs) of thermally assisted magnetic random access memories. Heating is produced by a pulse of electric current flowing through the junction. For sufficiently long heating pulse (>20 ns), a quasiequilibrium temperature profile is reached in the MTJ. In this stationary regime, a relationship between the temperature of the storage layer and the power of the pulse was established by using an Arrhenius-Neel model of thermal relaxation. The introduction of thermal barriers between the junction tunnel barrier and the electrodes allows a significant seduction of the power required to achieve a given temperature rise of the storage layer. When the heating pulse duration is reduced from 1 s to 2 ns, the heating power required for setting the F/AF storage bilayer increases by about 80%. This experimental observation is quantitatively interpreted by combining the Arrhenius-Neel model with thermodynamic simulations of heat diffusion with source term given by the experimentally known heating power dissipated in the tunnel barrier by Joule effect.