Back hopping in spin-transfer-torque devices, possible origin and counter measures

Abstract

The effect of undesirable high-frequency free-layer switching in magnetic multilayer systems, referred to as back hopping, is investigated by means of the spin-diffusion model. A possible origin of the back-hopping effect is found to be the destabilization of the pinned layer which leads to perpetual switching of both layers. The influence of different material parameters on the critical switching currents for the free and pinned layer is obtained by micromagnetic simulations. It is found that the choice of a free-layer material with low polarization $\beta$ and saturation magnetization $M_s$, and a pinned-layer material with high $\beta$ and $M_s$ leads to a low free-layer critical current and a high pinned-layer critical current and hence reduces the likelihood of back hopping. While back hopping was observed in various types of devices, there are only few experiments that exhibit this effect in perpendicularly magnetized systems. However, our simulations suggest, that this is likely to change due to loss of pinned-layer anisotropy when decreasing device sizes.

References in corpus (3)

• Time-resolved spin-torque switching in MgO-based perpendicularly magnetized tunnel junctions
• Field- and damping-like spin-transfer torque in magnetic multilayers
• Current-induced synchronized switching of magnetization

Cited by in corpus (6)

• Back-hopping in Spin-Transfer-Torque switching of perpendicularly magnetized tunnel junctions
• Inducing out-of-plane precession of magnetization for microwave assisted magnetic recording using an oscillating polarizer in spin torque oscillator
• Theoretical condition for switching the magnetization in a perpendicularly magnetized ferromagnet via the spin Hall effect
• A Perspective on Electrical Generation of Spin Current for Magnetic Random Access Memories
• Reduction of back switching by large damping ferromagnetic material
• Efficient solution strategy to couple micromagnetic simulations with ballistic transport in magnetic tunnel junctions