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Quantitative calculation of magnon transport properties of insulators

绝缘体磁振子输运特性的定量计算

基本信息

批准号：
17K14102
负责人：
Barker Joseph
金额：
$ 2.75万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Young Scientists (B)
财政年份：
2017
资助国家：
日本
起止时间：
2017-04-01 至 2019-03-31
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17K14102/
关键词：
spintronics magnons transport yttrium iron garnet antiferromagnet conductivity simulation spincaloritronics simulations magnetism

项目摘要

I have implemented a quantum thermostat for atomistic spin dynamics. I have rigorously checked its correctness in simple systems by comparison with analytically derivable results and in complex systems by comparing to experiments. The manuscript for this result is in the final stages of preparation for submission.I have succeeded in calculating magnon transport properties in the complex magnetic insulator Yttrium Iron Garnet (YIG). This includes the magnon spin conductivity and the magnon heat conductivity. This work required the quantum thermostat to achieve correct results at all temperatures. The magnon spin conductivity shows excellent agreement with experimental measurements but the heat conductivity shows a difference at higher temperature which may be due to defects or phonons. The manuscript of this work will soon be written and submitted for publication.I have also investigated magnon transport in antiferromagnetic insulators, notably Cr2O3, in collaboration with the experimental group of Prof. Eiji Saitoh (Tohoku) and theorists at the Johannes Gutenberg University, Mainz. In YIG/Cr2O3/Pt devices the Cr2O3 can be used to switch spin currents on and off. This work was published in Nature Materials. The unusual temperature dependence of anisotropy in Cr2O3 is important for this and I am currently preparing a manuscript where my calculations show the dipole anisotropy in this material has an anomalous behaviour.

我为原子自旋动力学实现了一个量子恒温器。我严格检查其正确性，在简单的系统中，通过与解析推导的结果比较，在复杂的系统中，通过与实验比较。我已经成功地计算了复杂磁绝缘体钇铁石榴石（YIG）中的磁振子输运性质。这包括磁振子自旋电导率和磁振子热导率。这项工作要求量子恒温器在所有温度下都能获得正确的结果。磁振子自旋电导率与实验测量结果非常吻合，但热导率在较高温度下显示出差异，这可能是由于缺陷或声子。本论文的手稿即将完成并提交出版。我还与美国美因茨约翰内斯古滕贝格大学的斋藤英二教授的实验小组和理论家合作，研究了反铁磁绝缘体中的磁振子输运，特别是Cr2 O3。在YIG/Cr_2O_3/Pt器件中，Cr_2O_3可用于开关自旋电流。这项工作发表在Nature Materials上。Cr2 O3中各向异性的不寻常的温度依赖性对此很重要，我目前正在准备一份手稿，我的计算显示这种材料中的偶极各向异性具有异常行为。