High velocity domain wall propagation using voltage controlled magnetic anisotropy

Abstract

The use of voltage-controlled magnetic anisotropy (VCMA) via the creation of a sloped electric field has been hailed as an energy-efficient approach for domain wall (DW) propagation. However, this method suffers from a limitation of the nanowire length which the DW can propagate on. Here, we propose the use of multiplexed gate electrodes to propagate DWs on magnetic nanowires without having any length constraints. The multi-gate electrode configuration is demonstrated using micromagnetic simulations. This allows controllable voltages to be applied to neighboring gate electrodes, generating large strength of magnetic anisotropy gradients along the nanowire, and the results show that DW velocities higher than 300 m/s can be achieved. Analysis of the DW dynamics during propagation reveals that the tilt of the DW and the direction of slanted gate electrode greatly alters the steady state DW propagation. Our results show that chevron-shaped gate electrodes is an effective optimisation that leads to multi-DW propagation with high velocity. Moreover, a repeating series of high-medium-low magnetic anisotropy regions enables a deterministic VCMA-controlled high velocity DW propagation.

Skyrmion-Magnetic Tunnel Junction Synapse With Long-Term and Short-Term Plasticity for Neuromorphic Computing

“…In recent years, different neuromorphic computing systems with MTJ devices based on skyrmions have been proposed, such as skyrmion neurons [16][13] and skyrmion synapses [11] [17]. Furthermore, the electric-field control of spintronic devices has been receiving increasing attention in memory and logic applications, as they provide an efficient way to improve the data storage density [18][19] and reduce the switching energy [20][21]. The skyrmion creation and annihilation by the voltage have been shown which promise for voltage-controlled skyrmion MTJ devices [22][23] [24] and in particular, voltagecontrolled strain-induced anisotropy based skyrmion synapse is proposed in [25] showing long term plasticity.…”

Controlling the Skyrmion Density and Size for Quantized Convolutional Neural Networks

“…Furthermore, the control of magnetic anisotropy using an electric field has attracted considerable attention for the voltage controlled spintronic memory and logic devices. It is an efficient approach for improving the data-storage density [24] [25] and reduces the switching energy considerably [26]. The important challenges associated with the realization of skyrmion devices for storage and computing (both conventional and unconventional computing) are the controlled motion and reading the skyrmions [27].…”

Voltage-Controlled Domain Wall Motion-Based Neuron and Stochastic Magnetic Tunnel Junction Synapse for Neuromorphic Computing Applications

“…The VCMA is driven by the electric field dependence of the 5d-orbital occupancy of the interface atoms [20]. The electric field control of these devices has attracted extensive attention in memory and logic applications, as it provides an efficient way to improve the data storage density [21] [22]. The domain wall velocity in a magnetic layer varies with change in the surface anisotropy by VCMA [23].…”