主讲人：梅佳伟 助理教授（南方科技大学）

题目：Dynamic fingerprint of fractionalized excitations in single-crystalline Cu₃Zn(OH)₆FBr

时间：2021年3月30日（周二）下午15:00

地点：理工楼1226报告厅

联系人：赵继泽

报告摘要：Beyond the absence of long-range magnetic orders, the most prominent feature of the elusive quantum spin liquid (QSL) state is the existence of fractionalized spin excitations, i.e., spinons. When the system orders, the spin-wave excitation appears as the bound state of the spinon-antispinon pair. Although scarcely reported, a direct comparison between similar compounds illustrates the evolution from spinon to magnon. Here, we perform the Raman scattering on single crystals of two quantum kagome antiferromagnets, of which one is the kagome QSL candidate {Cu₃Zn(OH)₆FBr}, and another is an antiferromagnetically ordered compound EuCu₃(OH)₆Cl₃. In Cu₃Zn(OH)₆FBr, we identify a unique one spinon-antispinon pair component in the E₂g magnetic Raman continuum, providing strong evidence for deconfined spinon excitations. In contrast, a sharp magnon peak emerges from the one-pair spinon continuum in the Eg magnetic Raman response once EuCu₃(OH)₆Cl₃undergoes the antiferromagnetic order transition. From the comparative Raman studies, we can regard the magnon mode as the spinon-antispinon bound state, and the spinon confinement drives the magnetic ordering.

个人简介：

梅佳伟，南方科技大学物理系助理教授（副研究员），主要从事量子磁性和超导方面的研究。梅佳伟博士在清华大学取得学士（2006年）和博士（2011年）学位后，曾在瑞士（2011年到2013年）、加拿大（2013年到2016年）和美国（2016年到2017年）从事博士后工作，2017年7月至今于南方科技大学工作。