Spin Caloritronics and Skyrmion Materials

****技术摘要****本项目旨在研究实验凝聚态物理中的两个重要课题：自旋热电子和Skyrmion材料。在自旋热电子学中，人们利用热输运和电子的电荷/自旋自由度之间的相互作用。其中，自旋塞贝克效应（SSE）是为数不多的能够产生纯自旋电流而不产生电荷电流的方法之一，因此具有重要意义。提出了在金属和绝缘体中捕获横向和纵向构型（分别具有面内和面外温度梯度）的本征SSE的新实验，并开发了合适的自旋电流检测器。Skyrmion材料是一种特殊的固体，没有反转对称性，并且存在Dzyaloshinskii-Moriya （DM）相互作用，从而产生螺旋基态，更有趣的是，产生了一种新的Skyrmion自旋结构。外延Skyrmion薄膜具有单晶或多晶材料无法获得的特性，将被用于研究拓扑霍尔效应、由于Berry相引起的自旋电子效应、自旋极化电流引起的Skyrmion晶格运动以及Skyrmion材料中的能思特效应。研究生、博士后和本科生（包括女性）将参与研究。****非技术摘要****本项目旨在研究凝聚态物理中两个新的重要课题：自旋热电子和Skyrmion材料。在自旋热电子学中，利用热流产生自旋电流而不产生电荷电流。纯电流可以产生新的自旋电子现象，但产生的热量要少得多。自旋塞贝克效应（SSE）是新近实现的几种能够产生纯自旋电流的方法之一。新的实验被设计用来在不同的测量配置中捕捉本征SSE，以识别可以检测纯自旋电流的材料，并将SSE与其他无关的效应分离开来。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Skyrmion材料的新型磁体中，磁矩并没有对齐，而是形成了复杂的双扭结构，具有独特的性能，便于探索和开发。Skyrmion薄膜将被用于追求新的物理效果，这可能会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.