[20p-E216-8~20] 10.2 Fundamental and exploratory device technologies for spin

▼ [20p-E216-8] Intrinsic Spin Decay Length in Antiferromagnetic Insulator

〇Hiroto Sakimura^1,2, Akio Asami², Hiroki Hayashi², Ji Shi¹, Kazuya Ando² (1.Tokyo Tech., 2.Keio Univ.)

Keywords:Antiferromagnet, Insulator, Spin current

In this work, we report intrinsic spin decay length of a prototypical antiferromagnetic insulator, NiO. We found that at an antiferromagnetic(AF)/ferromagnetic(FM) interface, a spin current generated by spin pumping is strongly suppressed by two-magnon scattering (TMS). By eliminating the two-magnon contribution by controlling the magnetization angle, we discovered that the characteristic length of spin decay in polycrystalline NiO changes by two-orders of magnitude through the paramagnetic to antiferromagnetic transition. The spin decay length in the antiferromagnetic state is around 100 nm, which is an order of magnitude longer than that previously believed. The activation of TMS is inevitable at AF/FM interface (independent of the combination of materials). Thus, our discovery points out the significance of removing the effect of TMS in spin pumping experiments, which provides a crucial piece of information for the fundamental understanding of the physics of spin transport.