We present a high throughput computational search for altermagnetism in two-dimensional (2D) materials based on the Computational 2D Materials Database (C2DB). We start by showing that the symmetry requirements for altermagnetism in 2D are somewhat more strict compared to bulk materials and applying these yields a total of 7 altermagnets in the C2DB. The collinear ground state in these monolayers are verified by spin spiral calculations using the generalized Bloch theorem. We focus on four $d$-wave altermagnetic materials belonging to the $P2_1'/c'$ magnetic space group - RuF$_4$, VF$_4$, AgF$_2$ and OsF$_4$. The first three of these are known experimentally as van der Waals bonded bulk materials and are likely to be exfoliable from their bulk parent compounds. We perform a detailed analysis of the electronic structure and non-relativistic spin splitting in $k$-space exemplified by RuF$_4$. The magnon spectrum of RuF$_4$ is calculated from the magnetic force theorem and it is shown that the symmetries that enforce degenerate magnon bands in anti-ferromagnets are absent in altermagnets and give rise to the obtained non-degenerate magnon spectrum. We then include spin-orbit effects and show that these will dominate the splitting ofmagnons in RuF$_4$. Finally, we provide an example of $i$-wave altermagnetism in the 2H phase of FeBr$_3$.
Stacking-Controlled Altermagnetism and Topological Magnons in Bilayer CrI$_3$
Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, State Key Laboratory of Optoelectronic Materials and Technologies, Institute of Neutron Science and Technology, School of Physics, Sun Yat-Sen University（中山大学物理学院中子科学与技术研究所光电材料与技术国家重点实验室磁电物理与器件广东省重点实验室）
Resonance-enhanced super-superexchange yields giant chiral magnon splitting in rutile altermagnets
University of Delaware（特拉华大学）；Quy Nhon University（归仁大学）；The University of Texas at El Paso（埃尔帕索德克萨斯大学）；National Institute of Standards and Technology（美国国家标准与技术研究院）；University of Maryland, College Park（马里兰大学帕克分校）
Alignment-Dependent Gapless Chiral Split Magnons in Altermagnetic Domain Walls
School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China（电子科技大学物理科学与技术学院及电子薄膜与集成器件国家重点实验室）
Pressure-Tunable Electronic and Magnonic Transport in Altermagnet La$_2$O$_3$Mn$_2$Se$_2$
Skolkovo Institute of Science and Technology（斯科尔科沃科学技术研究所）；Norwegian University of Science and Technology（挪威科技大学）；Sber University（俄罗斯联邦储蓄银行大学）；Isfahan University of Technology（伊斯法罕理工大学）
Observation of Switchable Chiral Magnons in an Altermagnet
Institute for Solid State Physics, the University of Tokyo（东京大学固体物理研究所）；Neutron Scattering Division, Oak Ridge National Laboratory（橡树岭国家实验室中子散射部）；Institut Laue-Langevin（朗之万研究所）；ISIS Neutron and Muon Source, Rutherford Appleton Laboratory（卢瑟福·阿普尔顿实验室ISIS中子和μ子源）；Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory（布鲁克海文国家实验室凝聚态物理与材料科学部）；Institute of Materials Structure Science, High Energy Accelerator Research Organization（高能加速器研究机构物质结构科学研究所）；Trans-scale Quantum Science Institute, the University of Tokyo（东京大学跨尺度量子科学研究所）
Emergent Skyrmion Hall Effect in $d$-wave Altermagnets at Finite Temperature
School of Physics Science and Information Technology, Liaocheng University（聊城大学物理科学与信息工程学院）；School of Physics and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China（电子科技大学物理学院电子薄膜与集成器件国家重点实验室）；Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials and Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University（华南师范大学广东省量子工程与量子材料重点实验室先进材料研究院南方先进光电子研究院）
$g$-wave altermagnetic order parameter in hematite
The Chinese University of Hong Kong（香港中文大学）；Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；Spallation Neutron Source Science Center（散裂中子源科学中心）；Guangdong Provincial Key Laboratory of Extreme Conditions（广东省极端条件重点实验室）；National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University（南京大学固体微结构物理国家级实验室与物理系）；Collaborative Innovation Center of Advanced Microstructures（先进微结构协同创新中心）
Symmetry-Guided Computational Screening of Two-Dimensional Altermagnets with ab initio Hubbard Corrections
Scuola Internazionale Superiore di Studi Avanzati (SISSA)（高级研究国际学院）；Università degli Studi di Modena e Reggio Emilia（摩德纳和雷焦艾米利亚大学）；Istituto Nanoscienze – CNR, S3（纳米科学研究所 - 意大利国家研究委员会）
Demonstration of ultrafast coherent sub-picosecond magnon pulses
Charles University（查理大学）；Czech Academy of Sciences（捷克科学院）；Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften（瓦尔特·迈斯纳研究所，巴伐利亚科学院）；Technical University of Munich（慕尼黑工业大学）；Freie Universität Berlin（柏林自由大学）；University of Nottingham（诺丁汉大学）；Tohoku University（东北大学）
Plaid-Like Spin Splitting and Chirality of Magnon Bands in Antiferromagnetic MnTe$_2$
Sejong University（世宗大学）；Korea Advanced Institute of Science and Technology (KAIST)（韩国科学技术院）；Sungkyunkwan University（成均馆大学）；Institute of Physics, Academia Sinica（中央研究院物理研究所）
$d$-wave altermagnetism revealed by resonant inelastic X-ray scattering
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所凝聚态物理国家实验室）；Department of Physics, Shanghai Normal University（上海师范大学物理系）；Department of Physics, The Chinese University of Hong Kong（香港中文大学物理系）；State Key Laboratory of Quantum Information Technologies and Materials, The Chinese University of Hong Kong（香港中文大学量子信息技术与材料国家重点实验室）；PSI Center for Neutron and Muon Sciences, Paul Scherrer Institute（保罗谢尔研究所中子与μ子科学中心）；Diamond Light Source, Harwell Campus（钻石光源哈韦尔园区）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）
