超表面、自旋波、石墨烯凯库勒超晶格、 kagome金属 | 本周物理讲座

1

报告人：柴国志，兰州大学

时间：3月24日（周二）10:00

单位：中国科学院物理研究所

地点：怀柔园区X1南楼101会议室

腾讯会议：300-570-941

摘要:

自旋波(磁振子)作为自旋角动量传递的基本表现形式反映了自旋的众多本征物理特性而引起广泛关注。磁振子由其运动方程决定具有天然的手征性。我们最近工作表明：利用层间相互作用和边界调制可实现表面自旋波的色散非互易行为，并基于此可得到自旋波的负群速度现象。在单层磁性薄膜中可实现静磁表面波和垂直交换驻波磁振子之间的耦合现象，并得到在相反波矢下耦合的非互易现象。在多层膜中则可以利用层间耦合实现声学支磁振子和光学支磁振子间的超强耦合。在最后也将分享一些本课题组在磁性双层膜中发现的一些新的磁振子耦合现象。

报告人简介:

柴国志，兰州大学“萃英学者”，二级教授，博士生导师。入选国家级青年人才计划，是甘肃省杰出青年基金获得者、甘肃省领军人才。2006年、2012年分获兰州大学学士和博士学位。2011年留校，在物理科学与技术学院工作至今，历任讲师，副教授和教授。近年来主持国家自然科学基金5项，其他各类项目7项。在高频磁性材料与磁功能器件研究方面发表SCI论文90余篇，获授权发明专利4项。目前主要从事高频磁性材料及其在传感器中的应用、磁性功能器件、布里渊光散射、微波光子-磁振子耦合等方面的研究。

2

报告人：张翼，南京大学物理学院

时间：3月24日（周二）13:30

单位：中国科学院物理研究所

地点：M楼249会议室

摘要:

借助各种表界面超晶格的构造来实现新颖量子物态的构筑是近年来凝聚态物理研究中的热点问题。以石墨烯为代表，通过构造具有(√3×√3)R30°超晶格周期的凯库勒畸变（Kekulé-distortion）可以实现狄拉克锥向布里渊区中心折叠并打开能隙。本报告将介绍多种表界面元素掺杂方式实现石墨烯凯库勒超晶格的构筑与狄拉克电子调控。我们利用角分辨光电子能谱技术，发现石墨烯表面的无序杂质可诱导增强狄拉克电子的谷间弹性散射，在转变温度以下，散射狄拉克电子间的相互干涉可形成凯库勒超晶格有序态，进而将布里渊K/K’点的两套不等价的狄拉克锥折叠到布里渊区中心。对于具有重电子掺杂效应的表面吸附钾元素，则会产生明显的等离激元并使狄拉克能带重整化，进而抑制狄拉克锥的折叠效应。钆元素在外延石墨烯的界面插层可增强其表面吸附能力，在低温下通过吸附氮元素来形成凯库勒周期并产生能带折叠。铕（Eu）元素在外延石墨烯的界面有序插层可直接形成凯库勒超晶格，更为重要的是，我们发现石墨烯狄拉克电子在能带折叠过程中，会插层铕元素4f轨道电子的局域磁矩产生很强的交换耦合作用，由此使得折叠狄拉克能带产生巨大的劈裂行]。这种狄拉克电子与局域磁矩之间的交换耦合作用，为狄拉克费米子的调控提供了新的自由度；而所实现的折叠狄拉克能带的巨幅劈裂，对于推动凯库勒石墨烯在自旋电子学领域的实际应用、探索基于狄拉克电子关联作用下的新颖量子物态，均具有重要的科学意义。

报告人简介:

张翼，南京大学物理学院教授。2006年毕业于北京大学。2011于中国科学院物理研究所取得博士学位。2011-2015年在美国伯克利国家实验室和美国斯坦福大学从事博士后研究。2015年加入南京大学物理学院。主要从事新型二维量子材料的分子束外延生长及新颖低维量子物态的构筑与调控研究，迄今已发表学术论文60余篇，H因子30。主持国家重点研发计划、基金委重大研究计划重点支持项目等多个国家项目。2021-2025年入选爱思唯尔中国高被引学者。2023年入选科睿唯安“全球高被引科学家”。

3

报告人：朱彬，南开大学

时间：3月26日（周四）10:00

单位：中国科学院理论物理研究所

地点：南楼6620

摘要:

With the new notions of flat holography introduced in recent years, there has been increased interest in relating the new formalisms to the flat space limit of AdS/CFT. We study Carrollian amplitudes of massless scalars in (1+2) Minkowski space. Using the prescription recently shown by Alday et al. originally designed for the AdS4 Witten diagrams, we show that AdS3 Witten diagrams in position space in the flat space limit reduce to Carrollian amplitudes. The flat space limit in the bulk is implemented by the Carrollian limit at the boundary. Focusing on four-point correlators with contact and exchange diagrams, we show that the Carrollian limit makes the universality of the bulk point singularity manifest upon performing analytic continuation to the Lorentzian signature of the boundary correlators. Unlike four-point Carrollian amplitudes in (1+3) dimensions, the (1+2) dimensional ones are non-distributional, having analytic properties simpler than the AdS correlators. We also report the first observation of a double copy structure of Carrollian amplitudes.

Generalizing the result to higher spacetime dimensions, we use the scattering equations and ambitwistor strings to prove the correspondence between an appropriate flat limit of boundary correlators in AdS and Carrollian scattering amplitudes – massless amplitudes written in position space on the null conformal boundary – for any number of external states and spacetime dimensions in tree-level, cubic scalar theories. We first derive the Carrollian version of the scattering equations in Minkowski space and their associated Carrollian amplitude formulae, by direct Fourier transform from momentum space and from ambitwistor strings with a Carrollian basis of vertex operators. We then take the flat limit of known formulae for all tree-level boundary correlators of cubic scalar theories in AdS, recovering the Carrollian amplitudes in flat space. In the special case of AdS3, we also make some comments on the flat space limit of spinning boundary correlators.

报告人简介:

朱彬，南开大学物理科学学院副教授。2022年博士毕业于美国东北大学，导师为Tomasz Taylor。2022年至2025年先后在加拿大圆周理论物理研究所和英国爱丁堡大学做博士后。于25年底加入南开大学物理科学学院，研究方向为散射振幅、共形场论和平直时空的全息理论，在PRL, JHEP, PRD, PLB, NPB等期刊发表19篇SCI论文。

4

报告人：何颂，Intitute of Theoretical Physics, Chinese Academy of Sciences

时间：3月26日（周四）15:00

单位：中国科学院理论物理研究所

Zoom：894 8844 8450

Passcode：441769

5

报告人：柳仲楷，上海科技大学

时间：3月26日（周四）15:00

单位：北京大学物理学院

地点：物理大楼中212报告厅

摘要:

Magnetic kagome materials provide a unique platform for exploring magneto-transport phenomena, symmetry breaking, and charge ordering driven by the intricate interplay among electronic structure, topology, and magnetism. Herein, we introduce a new design strategy for interweaving quasi-1D magnetic Tb zigzag chains with nonmagnetic Ti-based kagome bilayers in TbTi3Bi4. Neutron diffraction, spin-polarized scanning tunneling spectroscopy, and angle-resolved photoemission spectroscopy analyses confirm that the interwoven structure exhibits a coexistent elliptical spiral magnetic order, a spin-density wave, and an unusually large band-folding gap. The combined unique magnetic and electronic state leads to a giant anomalous Hall conductivity of 10⁵ Ω⁻¹cm⁻¹. These results establish TbTi3Bi4 as a model system of magnetic kagome metals with strong electron–magnetic interactions.

报告人简介:

柳仲楷，上海科技大学长聘副教授，研究员，万人计划领军人才，2006年于清华大学获理学学士学位；2014年于美国斯坦福大学获得物理学博士学位；2015年7月加入上海科技大学物质科学与技术学院。研究方向为开发并利用角分辨光电子能谱技术研究先进材料电子结构，在拓扑量子材料、低维量子材料、磁性量子材料等方面取得代表性成果。包括拓扑半金属、磁性拓扑绝缘体、拓扑超导材料、磁性Kagome材料等。主持开发上海同步辐射光源BL07U NanoARPES线站。主持基金委重点项目、科技部重点研发计划等多项项目，发表包括Science, Nature及其子刊，PRL等在内期刊论文百余篇，引用超23000次。

6

报告人：Jianglai Liu，上海交通大学

时间：3月26日（周四）15:30

单位：北京大学物理学院
地点：KIAA-auditorium

摘要:

Dark matter and neutrinos are among the most elusive neutral particles that permeate our Universe. The PandaX (Particle and Astrophysical Xenon) experiment, located in the China Jinping Underground Laboratory beneath a 2400-meter rock overburden, has been at the forefront of the search for dark matter particles for nearly two decades. As the sensitivity of the experiment continues to improve, the experiment has evolved into a versatile particle astrophysics observatory, with particular potentials on neutrino physics. In this talk, I will present the latest development in this field, and project the prospects of PandaX in the decades to come.

报告人简介:

Jianglai Liu obtained his B. S. degree in Physics from Nanjing University in 1998. He received a Ph.D. degree in Physics in 2006 from the University of Maryland at College Park. He held a postdoctoral and then senior postdoctoral scholar position at Caltech from 2006 to 2010. He joined the School of Physics and Astronomy (SPA), Shanghai Jiao Tong University in 2011, and became a full professor in 2016. He serves as the Deputy Director of the Tsung-Dao Lee Institute (TDLI), and is a Hongwen Distinguished Professor jointly appointed between TDLI and SPA. He has worked on various experiments in the intersections of nuclear physics, particle physics, and astrophysics. He currently serves as the spokesperson of the PandaX experiment, a xenon-based dark matter and neutrino experiment at the China Jinping Underground Laboratory. He also has a strong involvement in the Daya Bay and JUNO experiments, studying the fundamental properties of neutrinos. He was awarded the Outstanding Junior Investigator from the National Natural Science Foundation of China in 2015. He received the Wang Ganchang Prize from the Chinese Physics Society and the Xplorer Prize from the Tencent Foundation (2019). Since 2023, he has been sponsored as a New Cornerstone Investigator (www.newcornerstone.org.cn).

7

报告人：Alexander Belavin，L. D. Landau Institute for Theoretical Physics, Russian Academy of Sciences

时间：3月26日（周四）16:00

单位：中国科学院理论物理研究所

Zoom: 894 8844 8450

Passcode: 441769

8

报告人：Cheng-Wei Qiu, National University of Singapore

时间：3月26日（周四）16:00

单位：清华大学物理系

地点：物理楼W101

摘要:

In this talk, I will introduce a few new thoughts and developments on metasurfaces and metaphotonics, especially when multiple symmetries of low-dimensional materials meet with man-made structures. Translational research and metasurface spin-offs from our lab will be discussed too. Metasurfaces and low-dimensional materials have been developing as important candidates in the interfacial engineering, providing a plethora of new possibilities in novel optoelectronic functions and applications. The synergies between those domains hold great promises in manipulating light-matter interaction. I will start from reviewing and reporting some of the most recent developments in metasurfaces and nanophotonics, and then focus on how monolayer TMDC and layered 2D materials could be hybridized with classic metasurfaces to modulate and structure novel light behavior, such as zero-dark-current and bipolar semimetal photodetector, monolayer meta-lens of atomic thickness, hybrid designs with enhanced SHG, PL, and tunable structural colors, by the coordinated hybridization between those two parties. Finally, we will elaborate our new breakthrough based on the fusion and integration of symmetry and topological physics with van der Waals polaritonic metasurfaces, as a new roadmap toward ultra-low loss, long-range propagation, topological interfaces, and tailorable on-chip integrated functional devices.

报告人简介:

Cheng-Wei Qiu is Provost’s Chair Professor in National University of Singapore. He is the recipient of President’s Science Award 2023, the highest science distinction in Singapore. He was elected Fellow of Academy of Engineering Singapore, and Fellow of ASEAN Academy of Engineering and Technology. He is Fellow of APS, Optica, SPIE and The Electromagnetics Academy, US. He is Foreign Fellow of Chinese Optical Society. He is well known for his research in structured light and interfaces. He has published over 600 peer-reviewed journal papers, with H-index of 141. He was the recipient of MIT TR35@Singapore Award in 2012, Young Scientist Award by Singapore National Academy of Science in 2013, Engineering Researcher Award 2021 in NUS, World Scientific Medal 2021 by Institute of Physics, Singapore, Achievement in Asia Award (Robert T. Poe Prize) by International Organization of Chinese Physicists and Astronomers in 2022, Miller Visiting Professorship in UC Berkeley in 2025, Joseph Fraunhofer Award 2026 by Optica, etc. He was Highly Cited Researchers since 2019 by Web of Science. As an overseas partner, he has been awarded China’s Top 10 Optical Breakthroughs for 6 times (2019, 2020, 2021(one in Fundamental Research, and one in Applied Research), 2023 , 2025). He has been serving in Associate Editor for various journals such as JOSA B, PhotoniX, Photonics Research, and Editor-in-Chief for eLight. He also serves in Editorial Advisory Board for Laser and Photonics Review, Advanced Optical Materials, and ACS Photonics.

封面图片来源：https://www.kunming.cn/news/c/2024-08-28/13869052.shtml

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