Enhancement of Interfacial Dzyaloshinskii-Moriya Interaction: A Comprehensive Investigation of Magnetic Dynamics

We demonstrate various approaches to manipulate interfacial Dzyaloshinskii-Moriya interaction (IDMI) in magnetic films based on magnetic dynamic measurements, including Brillouin-light-scattering and broadband-ferromagnetic-resonance experiments. It is found that IDMI can be significantly enhanced with the ferromagnet (FM) layer sandwiched between heavy-metal (HM) layers. The induced IDMI clearly exhibits different chiralities for HM1/FM and HM2/FM, respectively, resulting in enhancement of IDMI after stacking in a sandwich structure. We show that IDMI can be greatly increased by capping the HM/FM system with an oxide layer. The strong Rashba effect due to an interfacial electric effect at the FM/oxide interface is responsible for the increased IDMI. Furthermore, such an IDMI induced by the Rashba effect can be efficiently tuned by an electric field. Finally, we find that IDMI can be effectively tailored with a strain, and the strength of IDMI increases linearly with strain in the sample. We further speculate that IDMI can be enhanced by more than 100% by combining several approaches demonstrated here. We also find that the extracted IDMI strength is more accurate by introducing asymptotic values of the gyromagnetic ratio (gamma) with a frequency approaching infinity from ferromagnetic resonance data. Our findings will benefit the spintronic community in the exploration of novel devices with chirality dependence.