Towards electric field assisted spin Hall torque switching of perpendicularly magnetized bits

Abstract

A new type of perpendicularly magnetized memory is explored, combining the spin Hall effect as a switching mechanism with the electric field effect as a selector. Calculations predict that this method is feasible. Magnetization reversal experiments show a coercivity modification between 4.5 mT and 13 mT for voltages between -2 V and +2 V. Two sensitivity regions are identified: a low sensitivity region of 0.5 mT/V for -0.8 V < V < 1.6 V and a high sensitivity region of 4.5 mT/V for higher voltages up to ±2.0 V. A logarithmic time dependence of the coercivity is found for voltages in the higher sensitivity region, which is attributed to a changing stoichiometry of the AlOx-Co interface due to migrating oxygen vacancies. The logarithmic time dependence is explained using a thermal fluctuation aftereffect model. Experimental results on spin Hall torque switching of a PMA microwire are in good agreement with the literature, showing that similar devices could be used in future projects.

Date of Award	30 Jun 2014
Original language	English
Supervisor	Henk J.M. Swagten (Supervisor 1) & A. van den Brink (Supervisor 2)