报告题目：Spin current driven by thermal nonequilibrium

报 告 人：Xiaoqin Li, Department of Physics, UT Austin

报告时间：2018-07-11 10:30

报告地点：理科楼C302报告厅

报告摘要：A central goal in spintronics is to develop devices that rely on the transfer of spin rather than charge. In magnetic insulators, magnons, i.e., quanta of collective spin excitations, carry a pure spin current and offer energy efficient information transport and processing. Several methods have been explored to generate spin currents in magnetic insulators, including the spin Hall effect, spin pumping, and the spin Seebeck effect (SSE). In particular, the SSE has emerged as an attractive method for generating spin current due to its simplicity and the ubiquitous presence of thermal gradients. Spin current can be driven by both temperature and magnon chemical potential gradients. Here, we report the spatially resolved measurement of the magnon chemical potential generated by laser heating in the magnetic insulator yttrium iron garnet. With the measured chemical potential, the spin current carried by the nonequilibrium magnons is quantified, and the wavevector and energy range of these nonequilibrium magnons are identified.