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量子新物态论坛(一):Determining the range of magnetic interactions from the relations between magnon eigenvalues at high-symmetry k points (万贤纲,南京大学)
发布时间: 2021-11-02 浏览次数: 83

【报告题目】Determining the range of magnetic interactions from the relations between magnon eigenvalues at high-symmetry k points

【报告人】南京大学 万贤纲教授

【时间】1112日(周五),14:00-15:30

【云报告地点】腾讯会议 会议ID:548318572

【摘要】Magnetic exchange interactions (MEIs) define networks of coupled magnetic moments and lead to a surprisingly rich variety of their magnetic properties. Typically MEIs can be estimated by fitting experimental results. But how many MEIs need to be included in the fitting process for a material is not clear a priori, which limits the quality of results obtained by these conventional methods. In this paper, based on linear spin-wave theory but without performing matrix diagonalization, we show that for a general quadratic spin Hamiltonian, there is a simple relation between the Fourier transform of MEIs and the sum of square of magnon energies (SSME). We further show that according to the real-space distance range within which MEIs are considered relevant, one can obtain the corresponding relationships between SSME in momentum space. We also develop a theoretical tool for tabulating the rule about SSME. By directly utilizing these characteristics and the experimental magnon energies at only a few high-symmetry k points in the Brillouin zone, one can obtain strong constraints about the range of exchange path beyond which MEIs can be safely neglected.

【报告人简介】

万贤纲 南京大学物理系教授,1990年至2000年在南京大学学习,获得学士、硕士、博士学位。

2001年起在南京大学历任讲师,副教授,2010年任教授。

主要学术成绩为;

提出了新型拓扑量子态-Weyl 半金属,引发了国际上-Weyl 半金属的研究热潮,该工作被评为“2011年中国百篇最具影响国际学术论文”,该工作也入选美国物理学会PRB期刊创刊50年“里程碑”(MILESTONE)文章,评语是:提出了一种新的量子物质状态外尔半金属The Weyl semimetal, a new state of quantum matter, is proposed)。发展了一套计算磁性相互作用的方法并确定多个复杂体系的基态磁构型。基于原子绝缘体基组发展了高效判断拓扑性能的理论方法,并用其对无机材料数据库里面所有非磁材料的拓扑特性进行了分类,该工作被评为“2019年中国百篇最具影响国际学术论文”,该工作入选“2019中国十大科技进展新闻”。

获得2014年度香港大学Daniel Tsui Fellowship

2015年获得国家杰出青年科学基金;

2016年被评为教育部长江学者特聘教授;

获中国物理学会2018-2019年度叶企孙物理奖;

2019年获首届腾讯基金会“科学探索奖”, 获2019年南京大学突出贡献奖;

2020年获第二届全国创新争先奖。

【邀请人】高先龙 教授

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