Switching of a magnetic tunnel junction by voltage-controlled magnetic anisotropy

The voltage-controlled magnetic anisotropy-based writing process of magnetic random-access memory relies on the precessional dynamics of the free-layer magnetization resulting from a voltage pulse. The success of the switching strongly depends on the spatial orientation of the magnetization when the pulse is turned off. For this reason, precise control over the voltage pulse parameters is fundamental to enable reliable writing operation. This study finds experimentally an optimal region for voltage amplitudes slightly above the voltage threshold for switching where a high switching probability is observed for a maximum range of pulse widths. Moreover, we report that the switching efficiency depends not only on pulse width, but also on pulse amplitude. We observe a second voltage amplitude threshold that limits the switching probability. Our macrospin simulations corroborate this finding and attribute this to a variation in the magnetization precessional dynamics at higher voltage amplitudes.