Critical switching current density of magnetic tunnel junction with shape perpendicular magnetic anisotropy through the combination of spin-transfer and spin-orbit torques

Abstract

Recently, magnetic tunnel junctions (MTJs) with shape perpendicular magnetic anisotropy (S-PMA) have been studied extensively because they ensure high thermal stability at junctions smaller than 20 nm. Furthermore, spin-transfer torque (STT) and spin-orbit torque (SOT) hybrid switching, which guarantees fast magnetization switching and deterministic switching, has recently been achieved in experiments. In this study, the critical switching current density of the MTJ with S-PMA through the interplay of STT and SOT was investigated using theoretical and numerical methods. As the current density inducing SOT ($$J_{\text {SOT}}$$ J SOT ) increases, the critical switching current density inducing STT ($$J_{\text {STT,c}}$$ J STT,c ) decreases. Furthermore, for a given $$J_{\text {SOT}}$$ J SOT , $$J_{\text {STT,c}}$$ J STT,c increases with increasing thickness, whereas $$J_{\text {STT,c}}$$ J STT,c decreases as the diameter increases. Moreover, $$J_{\text {STT,c}}$$ J STT,c in the plane of thickness and spin-orbit field-like torque ($$\beta$$ β ) was investigated for a fixed $$J_{\text {SOT}}$$ J SOT and diameter. Although $$J_{\text {STT,c}}$$ J STT,c decreases with increasing $$\beta$$ β , $$J_{\text {STT,c}}$$ J STT,c slowly increases with increasing thickness and increasing $$\beta$$ β . The power consumption was investigated as a function of thickness and diameter at the critical switching current density. Experimental confirmation of these results using existing experimental techniques is anticipated.

Dimensional scaling effects on critical current density and magnetization switching in CoFeB-based magnetic tunnel junction

“…Neglecting to a first approximation the thickness dependence of α, we expect a minimum in j crit corresponding to K eff = 0, which is around 1.3 nm, in good agreement with the numerical calculations. Our simulations depicting the size effect on the critical current density in figure 3 exhibit the same trend as previously studied in [33,36]. Furthermore, the operating speed of MTJs, which is associated with the switching time taken for magnetization reversal, is examined.…”

Compositional dependence of magnetostrictive effect in Ta/CoFe(B)/MgO stacks with perpendicular magnetic anisotropy

“…Besides, the magnetostriction effect of ferromagnet with the spin structures or textures gives a degree of control over its magnetic anisotropy energy [1]. Up to now, there has been intensive research interest in magnetic tunnel junctions (MTJs) with perpendicularly magnetized ferromagnetic electrodes (soft and hard layers) for realizing highly integrated non-volatile devices with high thermal stability and low critical current for current-induced magnetization switching [2][3][4][5][6]. To achieve high thermal stability, the thermal stability factor U/k B T of the soft layer needs to be more than 60 for non-volatility [7], where U is the energy barrier that isolates each magnetization direction in the soft and hard layers, k B the Boltzmann constant and T the temperature.…”

Cr2Ge2Te6 nanoribbons with perpendicular magnetic anisotropy and half metallicity: a DFT study

“…MgO is usually the best choice as an insulating layer since it provides high spin selectivity and large tunnel magnetoresistance [10,11]. The PMA effect, in the p-MTJs, is the heart of perpendicular spin-transfer torque [12] and spinorbit torque [13] magnetoresistive random-access memory (MRAMs). A high PMA is needed to enhance the thermal stability and improve data storage in MRAMs [14].…”