超表面、自旋波、石墨烯凱庫(kù)勒超晶格、 kagome金屬 | 本周物理講座

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報(bào)告人：柴國(guó)志，蘭州大學(xué)

時(shí)間：3月24日（周二）10:00

單位：中國(guó)科學(xué)院物理研究所

地點(diǎn)：懷柔園區(qū)X1南樓101會(huì)議室

騰訊會(huì)議：300-570-941

摘要:

自旋波(磁振子)作為自旋角動(dòng)量傳遞的基本表現(xiàn)形式反映了自旋的眾多本征物理特性而引起廣泛關(guān)注。磁振子由其運(yùn)動(dòng)方程決定具有天然的手征性。我們最近工作表明：利用層間相互作用和邊界調(diào)制可實(shí)現(xiàn)表面自旋波的色散非互易行為，并基于此可得到自旋波的負(fù)群速度現(xiàn)象。在單層磁性薄膜中可實(shí)現(xiàn)靜磁表面波和垂直交換駐波磁振子之間的耦合現(xiàn)象，并得到在相反波矢下耦合的非互易現(xiàn)象。在多層膜中則可以利用層間耦合實(shí)現(xiàn)聲學(xué)支磁振子和光學(xué)支磁振子間的超強(qiáng)耦合。在最后也將分享一些本課題組在磁性雙層膜中發(fā)現(xiàn)的一些新的磁振子耦合現(xiàn)象。

報(bào)告人簡(jiǎn)介:

柴國(guó)志，蘭州大學(xué)“萃英學(xué)者”，二級(jí)教授，博士生導(dǎo)師。入選國(guó)家級(jí)青年人才計(jì)劃，是甘肅省杰出青年基金獲得者、甘肅省領(lǐng)軍人才。2006年、2012年分獲蘭州大學(xué)學(xué)士和博士學(xué)位。2011年留校，在物理科學(xué)與技術(shù)學(xué)院工作至今，歷任講師，副教授和教授。近年來(lái)主持國(guó)家自然科學(xué)基金5項(xiàng)，其他各類(lèi)項(xiàng)目7項(xiàng)。在高頻磁性材料與磁功能器件研究方面發(fā)表SCI論文90余篇，獲授權(quán)發(fā)明專(zhuān)利4項(xiàng)。目前主要從事高頻磁性材料及其在傳感器中的應(yīng)用、磁性功能器件、布里淵光散射、微波光子-磁振子耦合等方面的研究。

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報(bào)告人：張翼，南京大學(xué)物理學(xué)院

時(shí)間：3月24日（周二）13:30

單位：中國(guó)科學(xué)院物理研究所

地點(diǎn)：M樓249會(huì)議室

摘要:

借助各種表界面超晶格的構(gòu)造來(lái)實(shí)現(xiàn)新穎量子物態(tài)的構(gòu)筑是近年來(lái)凝聚態(tài)物理研究中的熱點(diǎn)問(wèn)題。以石墨烯為代表，通過(guò)構(gòu)造具有(√3×√3)R30°超晶格周期的凱庫(kù)勒畸變（Kekulé-distortion）可以實(shí)現(xiàn)狄拉克錐向布里淵區(qū)中心折疊并打開(kāi)能隙。本報(bào)告將介紹多種表界面元素?fù)诫s方式實(shí)現(xiàn)石墨烯凱庫(kù)勒超晶格的構(gòu)筑與狄拉克電子調(diào)控。我們利用角分辨光電子能譜技術(shù)，發(fā)現(xiàn)石墨烯表面的無(wú)序雜質(zhì)可誘導(dǎo)增強(qiáng)狄拉克電子的谷間彈性散射，在轉(zhuǎn)變溫度以下，散射狄拉克電子間的相互干涉可形成凱庫(kù)勒超晶格有序態(tài)，進(jìn)而將布里淵K/K’點(diǎn)的兩套不等價(jià)的狄拉克錐折疊到布里淵區(qū)中心。對(duì)于具有重電子摻雜效應(yīng)的表面吸附鉀元素，則會(huì)產(chǎn)生明顯的等離激元并使狄拉克能帶重整化，進(jìn)而抑制狄拉克錐的折疊效應(yīng)。釓元素在外延石墨烯的界面插層可增強(qiáng)其表面吸附能力，在低溫下通過(guò)吸附氮元素來(lái)形成凱庫(kù)勒周期并產(chǎn)生能帶折疊。銪（Eu）元素在外延石墨烯的界面有序插層可直接形成凱庫(kù)勒超晶格，更為重要的是，我們發(fā)現(xiàn)石墨烯狄拉克電子在能帶折疊過(guò)程中，會(huì)插層銪元素4f軌道電子的局域磁矩產(chǎn)生很強(qiáng)的交換耦合作用，由此使得折疊狄拉克能帶產(chǎn)生巨大的劈裂行]。這種狄拉克電子與局域磁矩之間的交換耦合作用，為狄拉克費(fèi)米子的調(diào)控提供了新的自由度；而所實(shí)現(xiàn)的折疊狄拉克能帶的巨幅劈裂，對(duì)于推動(dòng)凱庫(kù)勒石墨烯在自旋電子學(xué)領(lǐng)域的實(shí)際應(yīng)用、探索基于狄拉克電子關(guān)聯(lián)作用下的新穎量子物態(tài)，均具有重要的科學(xué)意義。

報(bào)告人簡(jiǎn)介:

張翼，南京大學(xué)物理學(xué)院教授。2006年畢業(yè)于北京大學(xué)。2011于中國(guó)科學(xué)院物理研究所取得博士學(xué)位。2011-2015年在美國(guó)伯克利國(guó)家實(shí)驗(yàn)室和美國(guó)斯坦福大學(xué)從事博士后研究。2015年加入南京大學(xué)物理學(xué)院。主要從事新型二維量子材料的分子束外延生長(zhǎng)及新穎低維量子物態(tài)的構(gòu)筑與調(diào)控研究，迄今已發(fā)表學(xué)術(shù)論文60余篇，H因子30。主持國(guó)家重點(diǎn)研發(fā)計(jì)劃、基金委重大研究計(jì)劃重點(diǎn)支持項(xiàng)目等多個(gè)國(guó)家項(xiàng)目。2021-2025年入選愛(ài)思唯爾中國(guó)高被引學(xué)者。2023年入選科睿唯安“全球高被引科學(xué)家”。

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報(bào)告人：朱彬，南開(kāi)大學(xué)

時(shí)間：3月26日（周四）10:00

單位：中國(guó)科學(xué)院理論物理研究所

地點(diǎn)：南樓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.

報(bào)告人簡(jiǎn)介:

朱彬，南開(kāi)大學(xué)物理科學(xué)學(xué)院副教授。2022年博士畢業(yè)于美國(guó)東北大學(xué)，導(dǎo)師為T(mén)omasz Taylor。2022年至2025年先后在加拿大圓周理論物理研究所和英國(guó)愛(ài)丁堡大學(xué)做博士后。于25年底加入南開(kāi)大學(xué)物理科學(xué)學(xué)院，研究方向?yàn)樯⑸湔穹⒐残螆?chǎng)論和平直時(shí)空的全息理論，在PRL, JHEP, PRD, PLB, NPB等期刊發(fā)表19篇SCI論文。

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報(bào)告人：何頌，Intitute of Theoretical Physics, Chinese Academy of Sciences

時(shí)間：3月26日（周四）15:00

單位：中國(guó)科學(xué)院理論物理研究所

Zoom：894 8844 8450

Passcode：441769

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報(bào)告人：柳仲楷，上海科技大學(xué)

時(shí)間：3月26日（周四）15:00

單位：北京大學(xué)物理學(xué)院

地點(diǎn)：物理大樓中212報(bào)告廳

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 10? Ω?1cm?1. These results establish TbTi3Bi4 as a model system of magnetic kagome metals with strong electron–magnetic interactions.

報(bào)告人簡(jiǎn)介:

柳仲楷，上海科技大學(xué)長(zhǎng)聘副教授，研究員，萬(wàn)人計(jì)劃領(lǐng)軍人才，2006年于清華大學(xué)獲理學(xué)學(xué)士學(xué)位；2014年于美國(guó)斯坦福大學(xué)獲得物理學(xué)博士學(xué)位；2015年7月加入上海科技大學(xué)物質(zhì)科學(xué)與技術(shù)學(xué)院。研究方向?yàn)殚_(kāi)發(fā)并利用角分辨光電子能譜技術(shù)研究先進(jìn)材料電子結(jié)構(gòu)，在拓?fù)淞孔硬牧稀⒌途S量子材料、磁性量子材料等方面取得代表性成果。包括拓?fù)浒虢饘佟⒋判酝負(fù)浣^緣體、拓?fù)涑瑢?dǎo)材料、磁性Kagome材料等。主持開(kāi)發(fā)上海同步輻射光源BL07U NanoARPES線站。主持基金委重點(diǎn)項(xiàng)目、科技部重點(diǎn)研發(fā)計(jì)劃等多項(xiàng)項(xiàng)目，發(fā)表包括Science, Nature及其子刊，PRL等在內(nèi)期刊論文百余篇，引用超23000次。

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報(bào)告人：Jianglai Liu，上海交通大學(xué)

時(shí)間：3月26日（周四）15:30

單位：北京大學(xué)物理學(xué)院
地點(diǎn)：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.

報(bào)告人簡(jiǎn)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).

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報(bào)告人：Alexander Belavin，L. D. Landau Institute for Theoretical Physics, Russian Academy of Sciences

時(shí)間：3月26日（周四）16:00

單位：中國(guó)科學(xué)院理論物理研究所

Zoom: 894 8844 8450

Passcode: 441769

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報(bào)告人：Cheng-Wei Qiu, National University of Singapore

時(shí)間：3月26日（周四）16:00

單位：清華大學(xué)物理系

地點(diǎn)：物理樓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.

報(bào)告人簡(jiǎn)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.

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