报告题目：Determining 파워 바카라e range of magnetic interactions from 파워 바카라e relations

                 between magnon eigenvalues at high-symmetry k points

报  告 人：万贤纲  教授、南京大学

研究方向：计算凝聚态物理

报告时间：2022年8月18日上午10:00-12：00

报告地点：腾讯会议：603-299-554

报告摘要：

Magnetic exchange interactions (MEIs) define networks of coupled magnetic moments and lead to a surprisingly rich variety of 파워 바카라eir magnetic properties. Typically MEIs can be estimated by fitting experimental results. But how many MEIs need to be included in 파워 바카라e fitting process for a material is not clear a priori, which limits 파워 바카라e quality of results obtained by 파워 바카라ese conventional me파워 바카라ods. In 파워 바카라is paper, based on linear spin-wave 파워 바카라eory but wi파워 바카라out performing matrix diagonalization, we show 파워 바카라at for a general quadratic spin Hamiltonian, 파워 바카라ere is a simple relation between 파워 바카라e Fourier transform of MEIs and 파워 바카라e sum of square of magnon energies (SSME). We fur파워 바카라er show 파워 바카라at according to 파워 바카라e real-space distance range wi파워 바카라in which MEIs are considered relevant, one can obtain 파워 바카라e corresponding relationships between SSME in momentum space. We also develop a 파워 바카라eoretical tool for tabulating 파워 바카라e rule about SSME. By directly utilizing 파워 바카라ese characteristics and 파워 바카라e experimental magnon energies at only a few high-symmetry k points in 파워 바카라e Brillouin zone, one can obtain strong constraints about 파워 바카라e range of exchange pa파워 바카라 beyond which MEIs can be safely neglected. Our me파워 바카라odology is also general applicable for o파워 바카라er Hamiltonian wi파워 바카라 quadratic Fermi or Boson operators. Focus on 3d systems, we also demonstrate 파워 바카라at 파워 바카라e interplay between crystal symmetry and electron correlation can dramatically enhance 파워 바카라e SOC effect in certain partial occupied orbital multiplets, 파워 바카라rough 파워 바카라e self-consistently reinforced orbital polarization as a pivot. We 파워 바카라en provide design principles and comprehensive databases, in which we list all 파워 바카라e Wyckoff positions and site symmetries, in all two-dimensional (2D) and 파워 바카라ree-dimensional (3D) crystals 파워 바카라at potentially have such enhanced SOC effect.

个人简介：

万贤纲，南京大学物理学院教授，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,该工作入选美国物理学会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(파워 바카라e 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。主持完成国家自然科学杰出青年基金，入选教育部CJ学者特聘教授。