Enhanced magnon transport through an amorphous magnetic insulator

Magnonics research is focused on the transport of spin information via spin-wave, or magnon, excitations. Due to its exceptionally low damping, the magnetic insulator Yttrium Iron Garnet (YIG) is considered the most prominent material in this field. New research has been stimulated by a report of long (µm) magnon diffusion lengths in amorphous YIG (a-YIG) where there is no long range magnetic order. Similar experiments have failed to reproduce the results and spin-pumping data provides a much lower (3.6nm) spin diffusion length. We have recently measured a 28nm spin diffusion length in a-YIG (28nm) and hypothesise that samples of a-YIG may differ depending on growth conditions. In this proposal we will use polarized neutron reflectometry to investigate a-YIG in order to see if deviations away from the expected M = 0 emu/cc can explain the longer spin diffusion length in our samples.

磁振子学（Magnonics）研究聚焦于通过自旋波（spin-wave）或称磁振子（magnon）激发实现自旋信息的传输。由于其极低的阻尼特性，磁性绝缘体钇铁石榴石（Yttrium Iron Garnet，YIG）被视为该领域最具代表性的材料。非晶态YIG（a-YIG）中存在无长程磁有序的特性，而一份关于其具有长（微米级）磁振子扩散长度的报告激发了新的研究热潮。然而，类似实验未能重现该结果，且自旋泵浦数据（spin-pumping data）显示其自旋扩散长度（spin diffusion length）远更低（仅3.6纳米）。我们近期在a-YIG（28纳米）中测得28纳米的自旋扩散长度，并推测a-YIG样品的特性差异可能源于其生长条件的不同。本研究计划将采用极化中子反射法（polarized neutron reflectometry）对a-YIG进行研究，以探究偏离预期M=0 emu/cc（电磁单位/立方厘米）的现象是否能解释我们样品中较长的自旋扩散长度。