Room temperature ferromagnetic skyrmion-based artificial neuron device

Abstract

The development of energy-efficient and ultrafast neuromorphic computing based on the dynamics of the ferromagnetic (FM) skyrmion on the nanotrack has attained considerable interest. In this work, FM skyrmion based artificial neuron device is proposed. The perpendicular magnetic anisotropy (PMA) gradient is created on a thin film ferromagnetic (FM) layer by voltage control-PMA effect (VC-PMA). The anisotropy is directly co-related with the strength of 𝑚𝑧 that affects the size of skyrmion meaning that in the region with larger PMA, the skyrmion size is smaller and hence, more energy. However, the skyrmions have the tendency to move in the direction to minimize the energy. Hence, the skyrmion move towards the lower PMA. This behavior of skyrmion on a nanotrack with PMA gradient corresponds to the leaky-integrate-fire (LIF) functionality of the neuron device. Hence, the suggested energy-efficient artificial neuron opens up the path for developing for energy-efficient neuromorphic computing.

Skyrmion motion under temperature gradient and application in logic devices

“…This means that the magnon current density is inversely proportional to the damping constant due to the tendency of larger a G to align spins more, that will result in less oscillations about its mean position. As soon as the magnonic wave reaches the skyrmion, it interacts with the magnetization of the skyrmion and transfer its angular momentum to it thus, pushing the FM skyrmion towards the hotter side by exerting mSTT as shown in figure 2(a) [41,42,72].…”

“…The conventional approach to manipulate the skyrmion is by electrical currents through STT or SOT. However, there are many alternative ways for skymion manipulation including, temperature gradient (TG) [40][41][42], PMA gradient [43,44], DMI gradient [45], and strain [46]. Out of these, the TG driven mechanism that is at an early stage, is very promising owing to its low energy consumption thus, opening the path for the development of future energy-efficient skyrmionic devices by utilizing the waste heat.…”

SAF skyrmion-based leaky-integrate fire neuron device

“…Another advantage of SAFs lies in their composition of technology-relevant sputtered films, making them compatible with CMOS integration and standard spintronic devices like magnetic tunnel junctions [13]. Numerous alternative methods exist for manipulating skyrmion motion including PMA gradient [14], temperature gradient [15], and DMI gradient [16]. Among these options, driving skyrmions under a PMA gradient stands out as a preferred choice due to its ease of electrical integration and control [17].…”