Interacting Magnonic Currents and Chiral Spin Textures for Energy Efficient Spintronics

自旋电子学是凝聚态物理学的前沿课题之一，旨在利用电子的自旋自由度进行信息科学研究，形成了一门新的学科——自旋电子学。基于自旋极化电子的电荷输运现象，自旋电子学通过在磁性硬盘驱动器中提供极其灵敏的探测器，在数据存储方面取得了飞跃，但事实证明，在不造成巨大损失的情况下传输自旋信息是一项挑战。另一方面，磁振学到目前为止是一个有远见的概念，利用磁振子-自旋的集体激发，作为信息载体有利于节能电子产品。磁振子是磁性有序材料中电子自旋进动的波，在没有实际电荷输运和相关欧姆损耗的情况下传播，为大幅降低计算机能耗铺平了道路。最近在自旋电子学领域出现的另一个令人兴奋的话题是磁激子。磁skyrmions是一种拓扑保护的手性自旋织构，具有独特的实空间拓扑特性，在数据存储方面具有很大的潜力。针对这两方面的优势，我们建议研究磁振学和仿生学之间的联系，以实现节能自旋电子学。磁振子和手性自旋织构在偶极子、自旋轨道和交换能的相互作用下具有共同的基础，使它们成为完美的相互作用伙伴。磁振子速度快，对自旋方向敏感，很容易偏离平衡。手性自旋织构坚固耐用，不易挥发，在超短时间尺度上仍可重新编程。通过磁控溅射，相/动量分辨布里渊光散射（BLS）光谱，自旋敏感成像技术，我们的策略如下：(1)利用磁振子（自旋波）和手性自旋织构之间的不对称散射来优化非共线Dzyaloshinskii-Moriya相互作用，从而优化skyrmions材料；(2)我们将制作纳米级器件来测试磁振子和skyrmions之间的相互作用，通过这种相互作用来测试磁振子自旋传递扭矩、磁振子拓扑霍尔效应等新现象。因此，该研究的成功将为结合磁性现象的工具集提供巨大的可能性，为磁振学和复杂拓扑自旋织构的基本理解增加重要价值，并为节能自旋电子学建立一条途径。

Spintronics is one of the cutting-edge topics in condensed matter physics which aim to harness the spin degree of freedom of electrons for information science that has formed a new discipline - spintronics. Based on charge transport phenomena of spin polarized electrons, spintronics, has made its leap in data storage by providing extremely sensitive detectors in magnetic hard drives and turned out to be challenging to communicate spin information without great losses. On the other hand, magnonics which is so far a visionary concept, utilize magnons - the collective excitation of spins, as information carriers are advantageous for energy efficient electronics. Magnons are waves of the electrons’ spin precessional motion in magnetically ordered materials that propagate without actual charge transport and its associated Ohmic losses, paving the way for a substantial reduction of energy consumption in computers. Another exciting topic appeared recently in spintronics community is magnetic skyrmion. Magnetic skyrmions are topologically protected chiral spin textures with unique real-space topological properties and great potential in data storage. Aiming in taking advantages of these two topics: we propose to study the link between magnonics and skyrmionics for energy efficient spintronics.Our proposal is motivated by the facts that both magnons and chiral spin textures share a common ground set by the interplay of dipolar, spin-orbit and exchange energies rendering them perfect interaction partners. Magnons are fast, sensitive to the spins’ directions and easily driven far from equilibrium. Chiral spin textures are robust, non-volatile and still reprogrammable on ultrashort timescales. By using magnetron sputtering, phase/momentum resolved Brillouin light scattering (BLS) spectroscopy, spin sensitive imaging techniques, our strategy is the following: (I) we will utilize the asymmetric scattering between magnon (spin-wave) and chiral spin textures for optimizing the non-collinear Dzyaloshinskii-Moriya interaction and hence skyrmion materials, (II) we will fabricate nanoscale devices to test the mutual interaction between magnons and skyrmions, through which the novel phenomena such as magnonic spin transfer torque, magnonic topological Hall effect. A success of the proposed research could thus provide vast possibilities for combining the toolset of magnetic phenomena, adding important value to both magnonics and the fundamental understanding of complex topological spin textures and establish an avenue for energy efficient spintronics.