题目：Sub-100 nm-wavelength spin wave propagation in metal/insulator magnetic nanostructures
 
报告人：于海明 教授 (Fert Beijing research institute, School of electronic and information engineering, Beihang University）
时间：2016年4月22日（星期五）10:00
地点：中国科学院物理研究所 M253 会议室
摘要：
Spin waves [1] have the potential to provide beyond-CMOS applications, e.g. parallel processing in cellular networks [2]. However, magnonic devices realized so far using metallic ferromagnets such as permalloy suffer from the relatively short spin wave decay length. Insulating magnetic oxides provide a solution. Here we report on spin excitations in the insulating thin-film ferrimagnet yttrium iron garnet (YIG) that offers decay length of several 100s μm at room temperature [3]. Based on such YIG thin film, we excite propagating spin waves at GHz frequency with wavelengths λ down to 88 nm, when applying the recently reported nanomagnonic grating coupler [4]. The grating coupler consists of an array of Permalloy or CoFeB nanodisks with large saturation magnetization that are fabricated on top of the thin-film YIG. A large spin-wave signal strength is obtained when we excite the grating coupler at its own ferromagnetic resonance frequency. The wavelength of the propagating spin waves is smaller by five orders of magnitude compared to the electromagnetic wave that is used for excitation (in free space). [5] The findings are straightforwardly extended to even smaller wavelengths by further optimizing nanomagnets and array parameters as well as the material of the naonodisks. The results are important for the implementation of nanomagnonic devices combined with conventional microwave technology.
REFERENCES
1. A. V. Chumak, V. I. Vasyuchka, A. A. Serga & B. Hillebrands “Magnon spintronics” Nat. Phys. Vol 11, 453, 2015
2. Khitun, A., Bao, M. and Wang, K. L., “Magnonic logic circuits”, J. Phys. D: Appl. Phys., Vol. 43, 264005, 2010.
3. Yu, H. * et al., “Magnetic thin-film insulator with ultra-low spin-wave damping for coherent nanomagnonics”, Scientific Reports, Vol. 4, 6848, 2014.
4. Yu, H. et al., “Omnidirectional spin-wave nanograting coupler”, Nat. Commun., Vol 4, 2704, 2013.
5. Yu, H. * et al., “Approaching soft x-ray wavelengths in nanomagnet-based microwave technology”, Nat. Commun. Vol 7, 11255, 2016。
报告人简历：
教育及科研经历：
2002-2006年 北京大学 物理学院 本科
2006-2011年 瑞士洛桑联邦理工大学 EPFL 博士
2011-2014年 德国慕尼黑工业大学 TUM 博士后
2014年 北航副教授
2015年 教授，博士生导师
研究方向：
自旋电子学 (Spintronics)，纳米磁学 (Nano-magnetism), 自旋波电子学(Magnonics)
 联系人：蔡建旺（9094）