In van der Waals (vdW) materials, strong coupling between different degrees of freedom can hybridize elementary excitations into bound states with mixed character. Correctly identifying the nature and composition of these bound states is key to understanding their ground state properties and excitation spectra. Here, we use ultrafast spectroscopy to reveal bound states of d-orbitals and phonons in 2D vdW antiferromagnet NiPS3. These bound states manifest themselves through equally spaced phonon replicas in frequency domain. These states are optically dark above the Néel temperature and become accessible with magnetic order. By launching this phonon and spectrally tracking its amplitude, we establish the electronic origin of bound states as localized d-d excitations. Our data directly yield electron-phonon coupling strength which exceeds the highest known value in 2D systems. These results demonstrate NiPS3 as a platform to study strong interactions between spins, orbitals and lattice, and open pathways to coherent control of 2D magnets.
Discovery of Van Hove Singularities: Electronic Fingerprints of 3Q Magnetic Order in a van der Waals Quantum Magnet
University of California, Berkeley（加州大学伯克利分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Nanyang Technological University（南洋理工大学）；CIFAR（加拿大联邦先进研究基金会）；Kavli Energy NanoScience Institute（卡弗里能源纳米科学研究所）
A van der Waals Interface Hosting Two Groups of Magnetic Skyrmions
多个磁性Skyrmion相为基于Skyrmion的超高密度自旋存储器件增加了额外的自由度。将磁场扩展到二维范德华磁体是一个有益的挑战，其中可实现的自由度（例如厚度，扭曲角和电门控）和高skyrmion密度导致有趣的新特性和增强的功能。我们报告了一个范德华界面，该界面由两个居里温度分别为~65 K和~205 K的二维铁磁体Cr2 Ge 2 Te 6和Fe 3GeTe 2形成，其中包含两组磁skyrmion。在60 K以下观察到Cr2 Ge 2 Te 6磁有序时的两组拓扑霍尔效应。这两组skyrmions直接成像使用磁力显微镜。有趣的是，在零外加磁场的情况下，磁skyrmion仍然存在于异质结中。我们的研究结果是有希望的实现skyrmion设备的基础上，范德华异质结构托管多skyrmion阶段。
Magneto-optical Kerr spectroscopy of exciton Rydberg states in a magnetic van der Waals heterostructure
National Institute for Materials Science（物质材料研究机构）；Indian Institute of Science（印度科学学院）；University of Southern California（南加州大学）；Indian Institute of Technology (B.H.U.)（印度理工学院（贝拿勒斯印度教大学））；Chalmers University of Technology（查尔姆斯理工大学）
Charge and spin photogalvanic effects in the p-wave magnet NiI2
University of Milan-Bicocca（米兰比可卡大学）；Consiglio Nazionale delle Ricerche CNR-SPIN（意大利国家研究委员会 SPIN 研究所）；Vinča Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade（贝尔格莱德大学 Vinča 核科学研究所）；Centro de Física de Materiales (CSIC-UPV/EHU)（材料物理中心 (西班牙科学理事会-巴斯克自治区大学)）；IKERBASQUE, Basque Foundation for Science（伊克尔巴斯科奎，巴斯克科学基金会）；Donostia International Physics Center (DIPC)（圣塞巴斯蒂安国际物理中心）；Ca’ Foscari University of Venice（威尼斯大学）
Strongly Magnetically Tuned Coupling Strength and Nonlinearity in CrSBr Exciton-Polaritons
Peking University（北京大学）；Institute of Semiconductors, Chinese Academy of Sciences（中国科学院半导体研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Paderborn University（帕德博恩大学）；National Center for Nanoscience and Technology（国家纳米科学中心）；Shandong University（山东大学）；Xi’an Jiaotong University（西安交通大学）
Atomically Resolved Acoustic Dynamics Coupled with Magnetic Order in a van der Waals Antiferromagnet
Materials Science Division, Argonne National Laboratory（阿贡国家实验室材料科学部）；Department of Physics, University of Washington（华盛顿大学物理系）；Center for Ultrafast Phase Transformation, Department of Physics, Sogang University（西江大学物理系超快相变中心）；Department of Materials Science and Engineering, University of Washington（华盛顿大学材料科学与工程系）；Pohang Accelerator Laboratory, POSTECH（韩国科学技术院浦项加速器实验室）；Institute for Condensed Matter and Complex Systems, School of Physics and Astronomy, The University of Edinburgh（爱丁堡大学物理与天文学学院凝聚态与复杂系统研究所）；Donostia International Physics Center（圣塞巴斯蒂安国际物理中心）；Department of Physics, Cambridge, Massachusetts Institute of Technology（麻省理工学院物理系）；Departments of Physics and Applied Physics, Stanford University（斯坦福大学物理与应用物理系）
Magnetic control of an exciton-polariton condensate in a van der Waals magnet
University of Regensburg（雷根斯堡大学）；Technical University of Munich（慕尼黑工业大学）；University of Chemistry and Technology Prague（布拉格化工大学）；Regensburg Center for Ultrafast Nanoscopy（雷根斯堡超快纳米学中心）；Université Paris Cité（巴黎西岱大学）
Exciton-polariton condensate in the van der Waals magnet CrSBr
Carl von Ossietzky University Oldenburg（奥尔登堡卡尔·冯·奥西茨基大学）；University of Exeter（埃克塞特大学）；Xiamen University Malaysia（厦门大学马来西亚分校）；Beijing University of Technology（北京工业大学）；Technion-Israel Institute of Technology（以色列理工学院）；Guangdong Technion-Israel Institute of Technology（广东以色列理工学院）；Friedrich Schiller University Jena（耶拿弗里德里希·席勒大学）；Fraunhofer-Institute for Applied Optics and Precision Engineering IOF（弗劳恩霍夫应用光学和精密工程研究所）；Max Planck School of Photonics（马克斯·普朗克光子学校）；University of Chemistry and Technology Prague（布拉格化学技术大学）；University of Sheffield（谢菲尔德大学）
Anomalous spin-lattice coupling in a 2D antiferromagnetic semiconductor revealed by surface acoustic Rayleigh waves
University of California, Los Angeles（加州大学洛杉矶分校）；California NanoSystems Institute, University of California, Los Angeles（加州大学洛杉矶分校加州纳米系统研究所）；Auburn University（奥本大学）
