Electric spectroscopy of vortex states and dynamics in magnetic disks

Separated Edge-Soliton Meditated Dynamic Switching of Vortex Chirality and Polarity

Magnetic vortices are characterized by the senses of in-plane magnetization chirality and by the polarity of the vortex core. The electrical control of vortex polarity and chirality is highly demanded not only for fundamental understanding on spin dynamics in nano-disks under different circumstances, but also for technological applications, such as magnetic non-volatile memories and spin torque oscillators for neuromorphic computing. Here we report a novel approach that enables one to electrically control both the vortex chirality and polarity with low energy consumption. Thorough micromagneti…

Spin Vortex Resonance in Non-planar Ferromagnetic Dots

In planar structures, the vortex resonance frequency changes little as a function of an in-plane magnetic field as long as the vortex state persists. Altering the topography of the element leads to a vastly different dynamic response that arises due to the local vortex core confinement effect. In this work, we studied the magnetic excitations in non-planar ferromagnetic dots using a broadband microwave spectroscopy technique. Two distinct resonance frequency ranges were observed depending on the position of the vortex core controllable by applying a relatively small magnetic field. The microma…

Local Spectroscopy of the Electrically Tunable Band Gap in Trilayer Graphene

The stacking order degree of freedom in trilayer graphene plays a critical role in determining the existence of an electric field tunable band gap. We present spatially-resolved tunneling spectroscopy measurements of dual gated Bernal (ABA) and rhombohedral (ABC) stacked trilayer graphene devices. We demonstrate that while ABA trilayer graphene remains metallic, ABC trilayer graphene exhibits a widely tunable band gap as a function of electric field. However, we find that charged impurities in the underlying substrate cause substantial spatial fluctuation of the gap size. Our work elucidates t…

Strain-mediated magnetoelectric effect for the electric-field control of magnetic states in nanomagnets

Electric-field control of magnetism without electric currents potentially revolutionizes spintronics towards ultralow power. Here by using mechanically coupled phase field simulations, we computationally demonstrate the application of the strain-mediated magnetoelectric effect for the electric-field control of magnetic states in heterostructure. In the model heterostructure constituted of the soft nanomagnet Co and the piezoelectric substrate PMN-PT, both the volatility of magnetic states and the magnetization switching dynamics excited by the electric field are explored. It is found that an e…

Pb（ZrTi）O $_3$纳米粒子对卷曲电场的协同响应

Cooperative response of Pb(ZrTi)O$_3$ nanoparticles to curled electric fields

利用基于第一性原理的有效哈密顿量和有限温度蒙特卡罗模拟，研究了卷曲电场作用下零维Pb（Zr $_{0.5}$ Ti $_{0.5}$）O $_3$纳米粒子的协同响应以及涡旋开关的微观机制.我们发现，普遍接受的域共存机制是无效的环形开关。相反，偶极子显示出不寻常的集体行为，形成一个新的漩涡垂直（但不是相反）的环矩。新的和原来的涡之间的强相关性被揭示为逆转环矩的关键。对令人困惑的集体反应的微观见解进行了讨论。基于我们的发现，我们进一步描述了一种技术方法，该方法能够大幅降低涡旋切换所需的卷曲电场的大小。

Electric polarization of magnetic textures: new horizons of micromagnetism

A common scenario of magnetoelectric coupling in multiferroics is the electric polarization induced by spatially modulated spin structures. It is shown in this paper that the same mechanism works in magnetic dielectrics with inhomogeneous magnetization distribution: the domain walls and magnetic vortexes can be the sources of electric polarization. The electric field driven magnetic domain wall motion is observed in iron garnet films. The electric field induced nucleation of vortex state of magnetic nanodots is theoretically predicted and numerically simulated. From the practical point of view…

Manipulation of polar vortex chirality in oxide superlattices

Topological polar vortices that are the electric analogues of magnetic objects, present great potential in applications of future nanoelectronics due to their nanometer size, anomalous dielectric response, and chirality. To enable the functionalities, it is prerequisite to manipulate the polar states and chirality by using external stimuli. Here, we probe the evolutions of polar state and chirality of polar vortices in PbTiO3/SrTiO3 superlattices under electric field by using atomically resolved in situ scanning transmission electron microscopy and phase-field simulations. We find that the adj…

Ferroelectric switching dynamics of topological vortex domains in a hexagonal manganite

Field-induced switching of ferroelectric domains with a topological vortex configuration is studied by atomic imaging and electrical biasing in an electron microscope, revealing the role of topological defects on the topologically-guided change of domain-wall pairs in a hexagonal manganite.

磁场驱动触发磁涡中的自诱导Floquet磁子

Field-driven triggering of self-induced Floquet magnons in a magnetic vortex

通过微波光谱研究磁涡态磁隧道结，发现自诱导Floquet边带形成频率梳，其存在依赖于磁涡核心轨道。通过施加磁场移动磁涡核心，可在相同驱动条件下切换系统状态，展示出Floquet谱的滞后控制。

单分子光谱学作为研究超导体中电场的可能工具

Single Molecule Spectroscopy as a possible tool to study the electric field in superconductors

讨论了薄膜中超导跃迁对附近单个分子荧光光谱的影响。我们发现，单分子光谱学（SMS）应该是一个合适的工具来检测与涡旋线相关的电荷。我们还认为，一个电场必须出现在正常和超导区的中间相和SMS之间的边界可能是有用的，以研究这种效果。

偶极超流体中的电磁响应：涡旋晶格与奇异畴壁

Electromagnetic response in dipole superfluids: vortex lattices and singular domain walls

本文发展了 Ginzburg-Landau 唯象理论研究偶极超流体在伪磁场下的电磁响应，发现磁偶极超流体形成具有奇异六边形畴壁的涡旋晶格，而电偶极超流体则表现出类似超导体的涡旋核心场集中现象。

电场对BiFeO $_3$单晶影响的拉曼光谱研究

Electric field effect on BiFeO$_3$ single crystal investigated by Raman spectroscopy

利用显微拉曼光谱研究了低温下BiFeO $_3$单晶铁电畴的晶格动力学。的声子分配显示出一个大的频率分裂之间的横向和纵向分量的A $_1$声子模式相关的Bi-O键的分裂是可以忽略不计的薄膜相比。外加电场会引起与Bi-O键相关的低能模的频移。这些软化是由于经由压电效应的拉伸应力。我们给出了声子形变势的估计。