柔性压电效应与柔性磁电效应
Flexoelectricity and Flexomagnetism
AI总结：
本章综述应变梯度与曲率的耦合，介绍柔性压电效应的相关内容，以磁电效应为桥梁发展广义柔性磁电效应，讨论其相关现象及与反常磁性的关联。
摘要：
与均匀应变不同，应变梯度在空间反演下为奇对称，可解锁母体晶体中严格禁止的耦合作用。在纳米尺度，尤其是弯曲的低维体系中，这类梯度极易获得且往往不可避免，因此曲率可作为写入晶格本身的对称性破缺场。本章综述由此产生的与电极化和磁性的耦合作用。在确立应变梯度与曲率的几何关系后，我们首先综述作为更成熟参考案例的柔性压电效应：其定义复杂的体贡献、表面贡献与动态贡献，微观机制，在二维材料中的表现，以及目前可用于计算它的第一性原理方法。我们以磁电效应为概念桥梁，进而从广义上发展柔性磁电效应，涵盖磁性与应变梯度之间的任何耦合现象，具体讨论对曲率的线性磁化响应及曲率诱导的Dzyaloshinskii-Moriya相互作用，超出已有的曲线处理方法。最后，我们简要描述属于柔性磁电效应广义范畴的一些额外效应，包括非线性效应、非均匀磁电效应和Rashba型现象，以及与反常磁性（altermagnetism）的关联。
英文摘要：
Strain gradients, unlike homogeneous strain, are odd under space inversion and unlock couplings that are strictly forbidden in the parent crystal. At the nanoscale, and in curved low-dimensional systems in particular, such gradients are readily attainable and often unavoidable, so that curvature acts as a symmetry-breaking field written into the lattice itself. This chapter reviews the resulting couplings to electric polarization and magnetism. After establishing the geometric relation between strain gradients and curvature, we review flexoelectricity as the better-established reference case: the bulk, surface and dynamic contributions that complicate its definition, its microscopic mechanisms, its manifestation in two-dimensional materials, and the first-principles methodology now available for its calculation. Using the magnetoelectric effect as a conceptual bridge, we then develop flexomagnetism in a broad sense, covering any coupling phenomena between magnetism and strain gradients, and specifically discuss the linear magnetization response to curvature and curvature-induced Dzyaloshinskii-Moriya interactions, beyond the established curvilinear treatment. Finally, we briefly describe some additional effects fitting under this broad umbrella of flexomagnetism, including nonlinear ones, inhomogeneous magnetoelectric and Rashba-type phenomena, and connections to altermagnetism.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
