Pulse Shaping Strategies for Efficient Switching of Magnetic Tunnel Junctions by Spin-Orbit Torque

Abstract

The writing energy for reversing the magnetization of the free layer in a magnetic tunnel junction (MTJ) is a key figure of merit for comparing the performances of magnetic random access memories with competing technologies. Magnetization switching of MTJs induced by spin torques typically relies on square voltage pulses. Here, we focus on the switching of perpendicular MTJs driven by spin-orbit torque (SOT), for which the magnetization reversal process consists of sequential domain nucleation and domain wall propagation. By performing a systematic study of the switching efficiency and speed as a function of pulse shape, we show that shaped pulses achieve up to 50% reduction of writing energy compared to square pulses without compromising the switching probability and speed. Time-resolved measurements of the tunneling magnetoresistance reveal how the switching times are strongly impacted by the pulse shape and temperature rise during the pulse. The optimal pulse shape consists of a preheating phase, a maximum amplitude to induce domain nucleation, and a lower amplitude phase to complete the reversal. Our experimental results, corroborated by micromagnetic simulations, provide diverse options to reduce the energy footprint of SOT devices in magnetic memory applications.

10 pages, 7 figures

References in corpus (9)

• Spin Transfer Torques
• Single-shot dynamics of spin-orbit torque and spin transfer torque switching in three-terminal magnetic tunnel junctions
• Nanosecond-timescale low error switching of in-plane magnetic tunnel junctions through dynamic Oersted-field assisted spin-Hall effect
• Spin-transfer pulse switching: From the dynamic to the thermally activated regime
• Field-free switching of magnetic tunnel junctions driven by spin-orbit torques at sub-ns timescales
• Interplay of voltage control of magnetic anisotropy, spin transfer torque, and heat in the spin-orbit torque switching in three-terminal magnetic tunnel junctions
• Asymmetric velocity and tilt angle of domain walls induced by spin-orbit torques
• Steady State and Dynamics of Joule Heating in Magnetic Tunnel Junctions Observed via the Temperature Dependence of RKKY Coupling
• Deterministic and stochastic aspects of current-induced magnetization reversal in perpendicular nanomagnets