Spin Caloritronics and Skyrmion Materials

*技术摘要*本项目致力于研究实验凝聚态物理中的自旋热电子学和天空离子材料两个重要课题。在自旋量热电子学中，人们利用了热输运和电子的电荷/自旋自由度之间的相互作用。其中，自旋Seebeck效应(SSE)是少数几种可以在没有电荷电流的情况下产生纯自旋流的方法之一，因此具有重要的意义。为了在金属和绝缘体中捕获具有面内和面外温度梯度的横向和纵向结构中的本征SSE，以及开发合适的自旋电流探测器，已经提出了新的实验。Skyrmion材料是一种特殊的固体，没有反转对称性，存在Dzyaloshinskii-Moriya(DM)相互作用，导致了螺旋状的基态，更有趣的是，产生了一种新颖的Skyrmion自旋结构。外延Skyrmion薄膜具有单晶和多晶材料所不具备的特性，将被用来研究Skyrmion材料中的拓扑霍尔效应、Berry相引起的自旋电子效应、Skyrmion晶格的自旋极化电流运动以及Nernst效应。研究生、博士后和本科生，包括女性，将参与这项研究。*非技术摘要*这个项目寻求在凝聚态物理中追求两个新的和重要的主题--自旋热电子学和天米子材料。在自旋量热学中，人们利用热流来产生自旋电流，而不是电荷电流。纯电流能够产生新的自旋电子现象，但产生的热量要少得多。自旋Seebeck效应(SSE)是少数几种新实现的可以产生纯自旋流的方法之一。已经设计了新的实验来捕捉不同测量配置中的本征SSE，识别可以检测到纯自旋电流的材料，并将SSE与其他外部效应分开。在普通磁铁中，包括冰箱磁铁，小磁矩是对齐的。在一些被称为天空离子材料的新型磁体中，磁矩不是排列在一起的，而是形成了复杂的双扭曲结构，具有独特的勘探和开发性能。Skyrmion薄膜将被用于追求新的物理效果，这可能被用于新的设备应用，这可能会使现有的数据存储技术受益，甚至可能使新技术成为可能。

****Technical Abstract****This project seeks to pursue two important topics of spin caloritronics and Skyrmion materials in experimental condensed matter physics. In spin caloritronics, one exploits the interaction between heat transport and the charge/spin degree of freedom of electrons. Of those, spin Seebeck effect (SSE) is one of the few methods that can generate a pure spin current without a charge current, hence of great importance. New experiments have been proposed to capture the intrinsic SSE in both the transverse and the longitudinal configurations, with in-plane and out-of-plane temperature gradient respectively, in metals as well as insulators, and the development of suitable spin current detectors. Skyrmion materials are special solids without the inversion symmetry and with the presence of the Dzyaloshinskii-Moriya (DM) interaction, resulting a helical ground state, and more interestingly, a novel Skyrmion spin structure. Epitaxial Skyrmion thin films, with attributes unattainable in single crystals or polycrystalline materials, will be exploited to study the topological Hall effect, spintronic effects due to the Berry phase, motion of Skyrmion lattice by spin-polarized current, and the Nernst effect in Skyrmion materials. Graduate students, post-docs, and undergraduate students, including women, will be involved in the research.****Non-Technical Abstract****This project seeks to pursue two new and important topics of spin caloritronics and Skyrmion materials in Condensed Matter Physics. In spin caloritronics, one exploits heat flows to generate a spin current without an electric charge current. A pure current enables new spintronic phenomena but generates much less heat. Spin Seebeck effect (SSE) is one of the few newly realized methods that can generate a pure spin current. New experiments have been designed to capture intrinsic SSE in different measuring configurations, to identify materials that can detect a pure spin current, and to separate SSE from other extraneous effects. In common magnets, including refrigerator magnets, the small magnetic moments are aligned. In some new magnets, known as the Skyrmion materials, the magnetic moments are not aligned but form an intricate double-twist structure with unique properties for exploration and exploitation. Skyrmion thin films will be used to pursue new physical effects, which may be exploited for new device applications that may benefit existing data storage technology or may even enable new technologies.