A 1/3 Magnetization Plateau Phase as Evidence for the Kitaev Interaction in a Honeycomb-Lattice Antiferromagnet

报告题目：A 1/3 Magnetization Plateau Phase as Evidence for the Kitaev Interaction in a Honeycomb-Lattice Antiferromagnet

报告人：李建新教授南京大学

报告时间：2023年12月29日 8:30-10:00 am

报告地点：博习楼221会议室

报告摘要：The magnetization of a quantum magnet can be pinned at a fraction of its saturated value by collective effects. One example of such a plateau phase is found in spin-1/2 triangular-lattice antiferromagnets. They feature strong geometrical frustration and the plateau phase therein is often interpreted as arising from an order-by-disorder mechanism driven by quantum fluctuations. Here we observe a one-third magnetization plateau under an applied magnetic field in the spin-1 antiferromagnet Na₃Ni₂BiO₆ with a honeycomb lattice, which, with conventional magnetic interactions, would not be geometrically frustrated. Based on our elastic neutron scattering measurements, we propose the spin structure of the plateau phase to be an unusual partial spin-flop ferrimagnetic order. Our theoretical calculations indicate that bond-anisotropic Kitaev interactions are the source of frustration that produces the plateau. These results suggest that Kitaev interactions provide a different route to frustration and phases driven by quantum fluctuations in high-spin magnets.

报告人简介：李建新，南京大学物理学院教授，现兼任国务院学位委员会学科评议组成员、中国物理学会凝聚态理论与统计物理专业委员会副主任。1993年于武汉大学获博士学位。先后在台湾中研院物理研究所、美国加州大学伯克利分校从事访问研究。2004年入选教育部新世纪优秀人才支持计划。2005年获国家杰出青年科学基金。2008年度受聘为教育部长江学者特聘教授。2008年作为团队负责人获教育部创新团队。主要从事强关联电子系统、低维量子自旋系统物性以及高温超导物理的理论研究。