Spin Caloritronics and Skyrmion Materials

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****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.