兰州大学机构库 >物理科学与技术学院
涡旋磁振子的研究
Alternative TitleStudy of Twisted Magnons
陈敏
Subtype博士
Thesis Advisor贾成龙
2020-07-27
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name理学博士
Degree Discipline理论物理
Keyword自旋波 轨道角动量 Aharanov-Casher 效应 磁电效应
Abstract自旋是电子的内禀物理属性,也是实现信息存储和数据处理最为重要的物理基元。传 统上,利用自旋磁矩的翻转和进动来实现的数据存储和信息交换,由于调控手段的非局域 化特点和高能耗缺陷,已经远远不能满足未来对信息功能器件超快、低能耗和高密度集成 的需求。自旋波,作为磁有序的低能集体激发态,由于其 GHz 以上频段的高频性质、微纳 米尺度的波长、和无焦尔发热的传播特性,成为了自旋信息存储、运算和传递的理想载体。 作为磁有序系统的无能隙集体激发态,自旋波对应于磁性系统中携带一个量子自旋角动量 的玻色性元激发准粒子&mdash磁振子(magnon)。然而,对于磁振子的调控和携带信息的读 写,由于其微小的量子化自旋角动量和传播过程的指数阻尼衰减,效率和精确性成为了自 旋波电子学未来应用面临的内禀困难。 在本文中,我们通过 Aharanov-Casher 效应对交换自旋波引入轨道角动量(OAM)作为 新的物理自由度来克服传统自旋波电子学的潜在隐患。一方面,自旋波可以携带任意大小 的轨道角动量,形成拓扑非平庸的涡旋自旋波(twisted magnon)激发态另一方面轨道角 动量跟涡旋自旋波的拓扑核是紧密联系在一起的,而拓扑核是内禀的物理性质且不随系统 Gilbert 阻尼效应而衰减。涡旋自旋波的这些物理特性克服了传统自旋波的传播长度指数衰 减和携带自旋角动量微小这两大内禀应用缺陷,具有重要的理论价值和可期的应用前景。 在三维铁磁纳米波导管中,涡旋自旋波会以拓扑涡旋束流的方式传播,基于 Aharanov- Casher 效应,可以对涡旋自旋波轨道霍尔效应、旋磁效应以及传播性质进行电场调控,通 过不同的干涉图样实现信息的有效传递。涡旋自旋波还可以存在于具有 S O(2) 旋转对称 性的二维铁磁纳米圆盘中。它的空间构型和动力学演化模式所具有的拓扑性质可藉由自旋 泵浦效应和逆自旋霍尔效应实现电学读取。进一步的,我们还给出了涡旋自旋波在不同铁 磁纳米圆盘之间进行传递的特性。这些发现将为我们设计新的、基于拓扑自旋波的、高鲁 棒性的和抗衰减的磁振子器件提供理论支持。
Other AbstractSpin, the intrisic physical quantity of electron, is one of the most important unit carrier in information handling and storage. However, spin-flipping and -precession related methods can no longer fulfill the demand for multi-functional devices needed in next-generation information industry, due to their non-locality and extremely high energy consumption. Spin-waves, being the low-energy excitation in magnetic ordered system, outstand themselves for ultra-GHz eigen- fraquency, micro-/nano- wavelength and non-Joule transmission, which will become ideal can- didates for storing, computing and transfering information via spins. The quanta of spin-waves, Magnon, is a Bosonic elemental excitation in magnetic ordered system and carries one unit of spin angular moment. Howerver, the tiny angular moment of magnon, as well as the damping effects in magnets, prevent it from being effectively and accurately steered in information convert between electric- and magnetic- subsystems. In our paper, we propose to add a new twist to the planar exchange spin-waves as an orbital angular moment(OAM) to remove the barrier in the road of tranditional spin-wave spintronics. OAM can be tuned to any large enough value to produce topologically non-trivial spin-wave named TWSITED-MAGNON. On the other hand, OAM is bound to the topological charge of twisted-magnon, meaning it will not be dissipated by the Gilbert damping of the magnetic system due to that the topologcial chage is an intrisic physics of the twisted-magnon . These qualified properties of the twisted-magnon overcome the difficulties of tiny angular moment carried by spin-waves and exponential decay of their amplitude in transmission, which is of remarkable theoretical value and in hope of great application prospect. In 3-dimensional ferromagnetic wave guide, the orbital Hall effect, gyromagnetic effect and transmisson properties of the twisted-magnon can be steered via applied electric field. Further- more, we can transfer information effectively through variety of interference patterns shaped by several twisted-magnons&rsquosuperimposition. Twisted-magnons also adapted themselves in 2- dimensional ferromagnetic nano-disks which possess S O(2) symmetry. Their characteristics of spatial structures and topological properties in dynamical evolution are extractable via the spin pumping effect and the inverse spin Hall effect by electrical methods. Moreover, we also exhibit their transmission behavior between distinct ferromagnetic nano-disks. All these foundings will provide reliable theoretical corner-stone for novel, topological spin-wave-based and highly robust and damping-resisted magnonic devices.
Pages119
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/467460
Collection物理科学与技术学院
Affiliation
物理科学与技术学院
First Author AffilicationSchool of Physical Science and Technology
Recommended Citation
GB/T 7714
陈敏. 涡旋磁振子的研究[D]. 兰州. 兰州大学,2020.
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