Magnetization reversal in nanopillar devices

We consider different nanopillars, namely Py/X/Py, Co/X/Co, Ni/X/Ni and Fe/X/Fe, where X represents a nonmagnetic metal (X = Cu, Au, Ag, etc), and investigate the reversal of magnetization in the free layer and the impact of interface anisotropy on the switching process and reversal time by numerically solving the Landau-Lifshitz-Gilbert-Slonczewski equation. Switching of magnetization is initiated in the device only when the spin current exceeds a threshold value, and the reversal time depends on the bias current. The interface anisotropy of the free layer minimizes the threshold current and reduces the reversal time. The thickness of the free layer and polarization also play a key role in reducing the reversal time. Among the different nanopillars considered here, the Co nanopillar takes the minimum time for reversal. The observed reversal time in these nanopillars is of the order of a few picoseconds.