主讲人：吴宁 副教授（北京理工大学）

题目：A complete solution of the two-magnon problem in a higher-spin ferromagnetic chain with single-ion anisotropy

时间：2024年9月19日（周四）晚上20：00

腾讯ID：877-663-894

联系人：钟寅

报告摘要：

For a higher-spin ferromagnetic XXZ chain with single-ion anisotropy, several features regarding the evolution of the low-lying two-magnon bound states with varying wave number were observed in the literature. However, most of these observations are only qualitatively understood due to the lack of analytical tools. In this talk, I will present a new approach that combines exact two-magnon Bloch states [1] and a plane-wave ansatz to achieve a complete solution of the two-magnon problem in such a system [2]. We identify parameter regions that support different types of two-magnon bound states, with the boundaries defined by algebraic equations. We discover for the first time a narrow region in which two single-ion bound states coexist. We show that the phase diagrams for distinct wave numbers are similar to each other, which enables us to map the evolution of the bound states to the rectilinear movement of a representative point for given parameters in a rescaled phase diagram. This dynamic picture provides quantitative interpretations of the observed features.

参考文献:

[1] N. Wu*, H. Katsura*, S.-W. Li, X. Cai, and X.-W. Guan*, Exact solutions of few-magnon problems in the spin-S periodic XXZ chain, Phys. Rev. B 105, 064419 (2022).

[2] X. Lou, J. Li, and N. Wu*, Evolution of two-magnon bound states in a higher-spin ferromagnetic chain with single-ion anisotropy: A complete solution, Phys. Rev. B 110, L100404 (2024).

个人简介：

吴宁，北京理工大学物理学院理论物理系长聘副教授。2006年本科毕业于山东大学物理学专业，2011年于中国科学院高能物理研究所理论室获理学博士学位。2011-2016年先后在清华大学物理系，南洋理工大学材料科学与工程学院，普林斯顿大学化学系和马德里自治大学理论凝聚态物理系从事博士后研究。2016年加入北京理工大学物理学院。主要研究方向为低维自旋系统及其动力学，量子物理，强光与物质相互作用等。在Phys. Rev. A/B/E, J. Chem. Phys.等学术期刊发表论文近40篇。