Wang Hanchen, Chen Jilei, Liu Tao, Zhang Jianyu, Baumgaertl Korbinian, Guo Chenyang, Li Yuehui, Liu Chuanpu, Che Ping, Tu Sa, Liu Song, Gao Peng, Han Xiufeng, Yu Dapeng, Wu Mingzhong, Grundler Dirk, Yu Haiming
Fert Beijing Institute, BDBC, School of Microelectronics, Beihang University, Beijing 100191, China.
Laboratory of Nanoscale Magnetic Materials and Magnonics, Institute of Materials (IMX), School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
Phys Rev Lett. 2020 Jan 17;124(2):027203. doi: 10.1103/PhysRevLett.124.027203.
Spin waves can probe the Dzyaloshinskii-Moriya interaction (DMI), which gives rise to topological spin textures, such as skyrmions. However, the DMI has not yet been reported in yttrium iron garnet (YIG) with arguably the lowest damping for spin waves. In this work, we experimentally evidence the interfacial DMI in a 7-nm-thick YIG film by measuring the nonreciprocal spin-wave propagation in terms of frequency, amplitude, and most importantly group velocities using all electrical spin-wave spectroscopy. The velocities of propagating spin waves show chirality among three vectors, i.e., the film normal direction, applied field, and spin-wave wave vector. By measuring the asymmetric group velocities, we extract a DMI constant of 16 μJ/m^{2}, which we independently confirm by Brillouin light scattering. Thickness-dependent measurements reveal that the DMI originates from the oxide interface between the YIG and garnet substrate. The interfacial DMI discovered in the ultrathin YIG films is of key importance for functional chiral magnonics as ultralow spin-wave damping can be achieved.
自旋波能够探测Dzyaloshinskii-Moriya相互作用（DMI），这种相互作用会产生诸如斯格明子等拓扑自旋纹理。然而，在具有可说是最低自旋波阻尼的钇铁石榴石（YIG）中，尚未有DMI的报道。在这项工作中，我们通过使用全电自旋波光谱法，从频率、幅度，以及最重要的群速度方面测量非互易自旋波传播，从而通过实验证明了7纳米厚YIG薄膜中的界面DMI。传播的自旋波的速度在薄膜法线方向、外加磁场和自旋波波矢这三个矢量之间呈现手性。通过测量不对称群速度，我们提取出16 μJ/m²的DMI常数，并用布里渊光散射独立证实了这一结果。与厚度相关的测量结果表明，DMI源自YIG与石榴石衬底之间的氧化物界面。在超薄YIG薄膜中发现的界面DMI对于功能性手性磁子学至关重要，因为它能够实现超低的自旋波阻尼。
