Micromagnetic simulations of current-induced magnetization switching in Co∕Cu∕Co nanopillars

Abstract

We studied the current-induced magnetic switching in Co/ Cu/ Co nanopillars with an in-plane magnetization traversed by a perpendicular-to-plane spin-polarized current. The Landau-LifshitzGilbert equation incorporating the spin transfer torque ͑STT͒ effect was employed. Magnetization switching was found to take place when the current density exceeds a threshold. It is accompanied by drastic oscillations near the magnetic reversal point. The switching time depends on the applied current density. The magnetization can also be switched by a sufficiently long square pulsed current. The roles of anisotropy, exchange, and demagnetization energies in the magnetization switching process of nanopillars are discussed. It is shown that the switching is mainly determined by the competition between STT and the Gilbert damping torque.

Magnetization switching modes in nanopillar spin valve under the external field

“…The magnetic parameters are the saturation magnetization M s =1.446×10 6 A/m, the exchange constant A=2.0×10 11 J/m and the Gilbert damping parameter   =0.01 [16,17].…”

“…One of the most crucial requirements for lowering critical currents is the clear description of the process of the magnetization switching. We have investigated the magnetization dynamics of Co/Cu/Co nanoscale spin valve at various current densities by micro-magnetic simulations and illustrated the different dynamic modes when zero field is applied [16,17]. Guo et al [18] reported the magnetization dynamics of a pseudo-spin-valve structure with in-plane anisotropy, which is induced by the passage of a perpendicular-to-plane spin-polarized current.…”

Modelling current-induced magnetization switching in Heusler alloy Co2FeAl-based spin-valve nanopillar

“…However, the critical current density required to induce magnetization switching in the spin-valves is as high as 10 6 -10 8 A/cm 2 , and it is challenging to reduce J c to achieve the compatibility with highly scaled complementary metaloxide-semiconductor technology while maintaining thermal stability. [8][9][10][11][12] Recently, Heusler alloys 13 with lower saturation magnetization M s , smaller Gilbert damping constant a, and higher spin polarization constant g are demonstrated to be excellent candidates for reducing J c compared to the normal metal and metallic alloys, i.e., Fe, 14,15 Co, [16][17][18] CoFe, 19,20 Py, [21][22][23] and CoFeB. [24][25][26][27] Existing experimental work demonstrated that J c of Co 2 MnGe, Co 2 FeSi, and Co 75 Fe 25 spin-valves were 1.6 Â 10 7 , 2.7 Â 10 7 , and 5.1 Â 10 7 J/cm 2 , respectively.…”

Current induced magnetization switching in Co/Cu/Ni-Fe nanopillar with orange peel coupling

“…11 Since then, spin transfer torque induced switching has been widely studied both theoretically, [12][13][14] and experimentally [15][16][17] as well as through numerical and micromagnetic simulations. [18][19][20][21] In these studies, the speed of switching of magnetization in magnetic trilayers has been an issue of increasing importance, because of its potential applications. Even though several ways have been put forward to increase the speed of magnetization switching, anisotropy has been found to play a vital role.…”

“…Even though several ways have been put forward to increase the speed of magnetization switching, anisotropy has been found to play a vital role. 22 Among the different anisotropies, magnetic shape anisotropy, 21 magnetocrystalline anisotropy 23 and surface anisotropy 24 reduce the switching time drastically.…”