Toward error-free scaled spin torque majority gates

Abstract

The functionality of a cross-shaped Spin Torque Majority Gate is explored by means of micromagnetic simulations. The different input combinations are simulated varying material parameters, current density and size. The main failure mode is identified: above a critical size, a domain wall can be pinned at the center of the cross, preventing further propagation of the information. By simulating several phase diagrams, the key parameters are obtained and the operating condition is deduced. A simple relation between the domain wall width and the size of the Spin Torque Majority Gate determines the working range. Finally, a correlation is found between the energy landscape and the main failure mode. We demonstrate that a macrospin behavior ensures a reliable majority gate operation.

Fabrication of magnetic tunnel junctions connected through a continuous free layer to enable spin logic devices

“…This is due to the exchange-driven character of domain expansion since no lateral current is injected to drive DW. 22) Above this critical size 5𝛿, the nucleated DW is prone to pinning due to material defectivity and line edge roughness. [31][32] Below the critical size, the DW becomes unstable: magnetization is non-uniform during switching but converges to a uniform state after switching off the current.…”

Current-Driven Domain Wall Dynamics in Ferrimagnetic Nickel-Doped Mn4N Films: Very Large Domain Wall Velocities and Reversal of Motion Direction across the Magnetic Compensation Point

“…Domain walls (DWs) separate magnetic domains present in ferromagnetic materials. Current-driven DW motion was predicted theoretically by Berger in 1978 1 and then extensively studied for its potential applications in domain wall racetrack memories, 2 DW MRAM, 3 spin torque majority gate, 4,5 and other domain-wall-based logic devices. 6−9 The two mechanisms leading to DW motion driven by spin-polarized currents are the spin-transfer torque (STT) and the spin orbit torque (SOT) associated with the spin Hall effect (SHE).…”

Wide operating window spin-torque majority gate towards large-scale integration of logic circuits

“…Unlike the previous STMG design, 16,18,19 extremely small size is not required. Moreover, low anisotropy is not necessary.…”

“…Moreover, it takes advantage of the inherent non-volatility of the ferromagnetic layer and benefits from the stack development of Magnetic Random Access memories. The STMG concept has been explored through micromagnetic simulations 16,17 but was shown to have a narrow operating region, 18,19 requiring either very low effective anisotropy or very small Magnetic Tunnel Junctions (MTJs). The combination of these two criteria leads to limited non-volatility and challenging device fabrication.…”