Suppressing Magnetic Damping Related to Two-Magnon Scattering in Ultrathin NiFe Films by Interface Engineering

Abstract

Designing the ferromagnetic/nonmagnetic (FM/NM) heterostructure with desirable low magnetic damping is important for spintronic devices to reduce the critical current density of magnetization switching. For ultrathin FM/NM films, magnetic damping from the two-magnon scattering (TMS) effect is a critical component, and suppressing TMS damping becomes one of the crucial ways to achieve low damping. In this paper, we have demonstrated the depressed linewidth in Ta (1 nm)/NiFe (3 nm)/NM (4 nm)/Ta (1.5 nm) heterostructure with Cu instead of Pt as the NM layer, where the maximal linewidth of ferromagnetic resonance (FMR) decreases from 440 to 190 Oe. And the decrease of TMS damping from 55 to 0 Oe is one of the main reasons for the lower FMR linewidth. The nonzero surface magnetic anisotropy implies that the suppression of interfacial defect scattering causes reduced TMS damping. Meanwhile, a noticeable enhancement of TMS damping from the lack of seed layer may be due to the lattice structure change. Thereby, our findings provide a way toward the design of low-damping spintronic devices.