High temperature stability in few atomic layer MoS 2 based thin film heterostructures: structural, static and dynamic magnetization properties.

Layered transition metal dichalcogenides (TMDs) have shown commendable properties for spintronic applications. From the device perspective, the structural quality of the TMD as well as its interface with the adjacent ferromagnetic (FM) layer is of paramount importance. Here, we present the spin-dynamic behaviour in the widely studied TMDs, i.e. , MoS 2 using Co 60 Fe 20 B 20 (CoFeB), i.e. , in MoS 2 (1-4 layers)/CoFeB(4-15 nm) heterostructures, both in the as-grown state and in the in situ annealed state (400 °C in a vacuum). Raman spectroscopy revealed systematic variation in the separation ( δ ) between the characteristic Raman shifts corresponding to the E 2g and A 1g vis-à-vis the number of layers ( n L ) of MoS 2 . The analysis of the ferromagnetic resonance (FMR) spectroscopy measurements performed on these heterostructures revealed the spin pumping from CoFeB to the MoS 2 layer as evidenced by the ∼49% (∼51%) enhancement in the effective damping parameter with respect to the damping parameter of bare as-deposited (annealed) CoFeB films. This enhancement is attributed to the spin-pumping owing to the high spin-orbit coupling of monolayer MoS 2 . The latter is also confirmed by density functional theory calculations. By finding the effective spin mixing conductance of the MoS 2 /CoFeB interface, the effective spin current density in the MoS 2 layer is estimated to increase from ∼0.3 to 0.7 MA m -2 with CoFeB thickness for both the as-deposited and annealed heterostructures. Furthermore, the δ vs . n L curve of the as-deposited heterostructure did not show any significant change upon annealing, which demonstrated that the spin transport and magnetic properties of these heterostructures remained unaffected even after annealing at a high temperature of 400 °C. Hence, this establishes the high thermal stability of the sputter grown MoS 2 /CoFeB heterostructures. Thus, this study highlights the important role of MoS 2 as an efficient spin current-generating source for spin-orbit torque based magnetic memory applications, given the high-temperature stability and high-quality monolayers of MoS 2 and its excellent performance with CoFeB thin films.