Two-dimensional transition metal dichalcogenides (TMDs) have drawn immense interest due to their strong spin-orbit coupling and unique layer number dependence in response to spin-valley coupling. This leads to the possibility of controlling the spin degree of freedom of the ferromagnet (FM) in thin film heterostructures and may prove to be of interest for next-generation spin-based devices. Here, we experimentally demonstrate the odd-even layer dependence of WS2 nanolayers by measurements of the ultrafast magnetization dynamics in WS2/Co3FeB thin film heterostructures by using time-resolved Kerr magnetometry. The fluence (photon energy per unit area) dependent magnetic damping (α) reveals the existence of broken symmetry and the dominance of inter- and intraband scattering for odd and even layers of WS2, respectively. The higher demagnetization time, τm, in 3 and 5 layers of WS2 is indicative of the interaction between spin-orbit and spin-valley coupling due to the broken symmetry. The lower τm in even layers as compared to the bare FM layer suggests the presence of a spin transport. By correlating τm and α, we pinpointed the dominant mechanisms of ultrafast demagnetization. The mechanism changes from spin transport to spin-flip scattering for even layers of WS2 with increasing fluence. A fundamental understanding of the two-dimensional material and its odd-even layer dependence at ultrashort timescales provides valuable information for designing next-generation spin-based devices.
- Publikační typ
- časopisecké články MeSH
A damping-like spin-orbit torque (SOT) is a prerequisite for ultralow-power spin logic devices. Here, we report on the damping-like SOT in just one monolayer of the conducting transition-metal dichalcogenide (TMD) TaS2 interfaced with a NiFe (Py) ferromagnetic layer. The charge-spin conversion efficiency is found to be 0.25 ± 0.03 in TaS2(0.88)/Py(7), and the spin Hall conductivity (14.9×105ℏ2eΩ-1m-1) is found to be superior to values reported for other TMDs. We also observed sizable field-like torque in this heterostructure. The origin of this large damping-like SOT can be found in the interfacial properties of the TaS2/Py heterostructure, and the experimental findings are complemented by the results from density functional theory calculations. It is envisioned that the interplay between interfacial spin-orbit coupling and crystal symmetry yielding large damping-like SOT. The dominance of damping-like torque demonstrated in our study provides a promising path for designing the next-generation conducting TMD-based low-powered quantum memory devices.
- Klíčová slova
- Damping-like torque, Planar Hall effect, Spin-torque ferromagnetic resonance, Transition-metal dichalcogenide,
- Publikační typ
- časopisecké články MeSH
