Van-der-Waals magnets: Frustrated magnetism, magnetotransport, and optically driven excitations

范德华磁体：受抑磁性、磁输运和光驱动激励

• 批准号: 449890867
• 负责人: Dr. Urban Seifert
• 金额: --
• 依托单位: Kavli Institute for Theoretical Physics
• 依托单位国家: 德国
• 项目类别: WBP Fellowship
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/449890867?language=en
• 关键词: Van; der; Waals; magnets; Frustrated; Van; der; Waals; magnets; Frustrated

Condensed matter systems in low dimensions often show behavior and exotic phenomena markedly different from their three-dimensional bulk analogues. A particularly fruitful platform to study these effects and design systems with desired characteristics are two-dimensional few-layer heterostructures based on exfoliated van-der-Waals materials. These novel devices allow for an unprecedented degree of control of strongly correlated electrons by e.g. varying the relative displacement between layer (including twisting) or electric gating. Only in 2017, first evidence for magnetism in mono- and few-layer van-der-Waals (vdW) systems was found. Since then, remarkable experimental progress has uncovered several other vdW materials exhibiting various ferro- and antiferromagnetic ordering patterns. Many of these systems feature strongly enhanced magnetooptical effects, novel tunneling magnetoresistance and magnetoelectric effects, and strong coupling between magnetic and lattice degrees of freedom.This project has the goal of gaining a thorough understanding of novel phenomena in few-layer van-der-Waals systems, with the aim of both identifying novel phenomena and proposing experimental protocols, as well as theoretically modelling previously observed effects.To this end, in the first part of this project, we employ a continuum model to study the impact of strong spin-lattice coupling on the non-collinear ground states and excitations in the recently proposed frustrated Moiré magnets obtained by twisting a bilayer magnet.Second, we will investigate novel phases induced by a magnetic field in these twisted bilayer magnets and compute the corresponding spin-wave dispersions by modelling interlayer magnon tunneling for arbitrary lattice displacements.The third part of this project is concerned with the novel magnetism-dependent interlayer electronic transport observed in some semiconducting magnetic van-der-Waals few-layer systems, in particular CrI3. Here, we plan to model low-energy electronic excitations in an effective mass model and then couple this model to a continuum theory for magnetism in the few-layer systems.Lastly, we will explore to what extent ultrafast optical methods can be used to excite magnetic excitations in magnetic vdW systems, in particular also utilizing spin-lattice coupling, and study non-equilibrium dynamics in these heterostructures.

低维度的冷凝材料系统通常显示出行为和外来现象明显不同于它们的三维散装类似物。一个特别富有成果的平台来研究具有所需特征的这些效果和设计系统，是基于独家Van-der-Waals材料的二维几层异质结构。这些新型设备允许通过例如通过改变层（包括扭曲）或电控之间的相对位移。仅在2017年，才发现了单层和几层Van-der-Waals（VDW）系统中磁性的第一个证据。从那时起，显着的实验进步发现了其他几种表现出各种铁磁性排序模式的VDW材料。 Many of these systems feature strongly enhanced magnetooptical effects, novel tunneling magnetoresistance and magnetoelectric effects, and strong coupling Between magnetic and lattice degrees of freedom.This project has the goal of gaining a thorough understanding of novel phenomena in few-layer van-der-Waals systems, with the aim of both identifying novel phenomena and proposing experimental protocols, as well as theoretical modelling previously observed effects.To this end, in该项目的第一部分，我们采用连续模型来研究强旋转耦合对非连线基接地状态的影响和最近提出的挫败感的挫败感中的兴奋和兴奋，从而通过扭曲双层磁铁来获得。我们将通过这些扭曲的Bielayer Magnets中的磁场诱导的新颖阶段来调查这些扭曲的型号的旋转型旋转型旋转器，并调查这些扭曲的型号的旋转型号的旋转型旋转型号，使得旋转型号的旋转型旋转型旋转型旋转型旋转型号的旋转型号，晶格位移。该项目的第三部分与在某些半导体的磁性货车范围内观察到的新型磁性依赖性的层间电子传输有关，特别是CRI3。 Here, we plan to model low-energy electronic excitements in an effective mass model and then couple this model to a continuous theory for magnetism in the few-layer systems.Lastly, we will explore to what extent ultrafast optical methods can be used to excite magnetic excitements in magnetic vdW systems, in particular also utilizing spin-lattice coupling, and study non-equilibrium dynamics in these heterostructures.