Enhanced spin-orbit torque efficiency in Pt_100–x Ni _x alloy based magnetic bilayer*

Abstract

The binary alloy/ferromagnetic metal heterostructure has drawn extensive attention in the research field of spin–orbit torque (SOT) due to the potential enhancement of SOT efficiency via composition engineering. In this work, the magnetic properties and SOT efficiency in the Pt100 – x Ni x /Ni78Fe22 bilayers were investigated via the spin-torque ferromagnetic resonance (ST-FMR) technique. The effective magnetic anisotropy field and effective damping constant extracted by analyzing the ST-FMR spectra show a weak dependence on the Ni concentration. The effective spin-mixing conductance of 8.40 × 1014 Ω−1 ⋅ m−2 and the interfacial spin transparency T in of 0.59 were obtained for the sample of Pt70Ni30/NiFe bilayer. More interestingly, the SOT efficiency that is carefully extracted from the angular dependence of ST-FMR spectra shows a nonmonotonic dependence on the Ni concentration, which reaches the maximum at x = 18. The enhancement of the SOT efficiency by alloying the Ni with Pt shows potential in lowering the critical switching current. Moreover, alloying relatively cheaper Ni with Pt may promote to reduce the cost of SOT devices.

Enhanced Spin–Orbit Torque Efficiency in Platinum–Gadolinium Oxide Nanocomposite Films

“…The extracted 4π M eff seen in Figure S2­(f) for the NiFe ( t nm)/Pt 0.7 (GdO y ) 0.3 bilayers increases from 0.85 to 0.95 T as the thickness of the NiFe layer reduces from 9 to 7 nm and then decreases gradually from 0.95 to 0.56 T as the thickness of the NiFe layer reduces from 7 to 2 nm. This reduction in 4π M eff can be understood in terms of an interface-perpendicular magnetic anisotropy that reflects the gradually increasing contribution of the interfacial anisotropy with decreasing thickness. , …”

“…Such a thickness dependence of α is attributed to two-magnon scattering and the spin pumping effect. 28,41,43 Next, we turn to analyze and discuss the SOT efficiency of the samples. Samples consisting of Ta (1 nm)/NiFe (t nm)/ Pt 1−x (GdO y ) x (6 nm), with t = 2, 3, 4, 5, 6, 7, 8, and 9, are deposited on silicon substrates using magnetron sputtering.…”

“…This reduction in 4πM eff can be understood in terms of an interface-perpendicular magnetic anisotropy that reflects the gradually increasing contribution of the interfacial anisotropy with decreasing thickness. 41,42 The frequency dependences of resonance line widths are summarized in Figure 2(e). The resonance line width can be fitted by 39…”

In-plane current-induced magnetization reversal of Pd/CoZr/MgO magnetic multilayers

“…[6] The SOT efficiency can also be enhanced by alloying Ni with Pt, which is favorable for lowering the critical switching current. [7] However, the critical current density of driving the magnetization reversal is still higher than 10 6 A/cm 2 . [8] On the other hand, the heavy metal/ferromagnetic metal (HM/FM) bilayer structure with perpendicular magnetic anisotropy (PMA) exhibits potentially high efficiency of the current-driven magnetization switching.…”

Enhancement of spin-orbit torque efficiency by tailoring interfacial spin-orbit coupling in Pt-based magnetic multilayers

“…In addition, the interface-related spin memory loss (SML) and spin flow back also play an essential role in the effective SOTs efficiencies. For instance, the SOTs efficiencies can be significantly enhanced by improving interfacial spin transmission efficiency and enhancing IREE via interface engineering, such as inserting ultrathin nonmagnetic metal layer (e.g., Hf, [19] Mo, [20] and Cu [21,22] ) between the HM and FM layers, oxygen-induced interface orbital hybridization, [23] alloy, [24] and interfacial H + and O 2− ion manipulations. [25] Very recently, inserting a magnetic spacer [26,27] between the FM and HM layers has also been proposed as a promising method to improve the effective SOTs efficiencies by selecting suitable magnetic materials to increase ISOC and/or enhance interfacial spin transparency (T int ).…”