Predicted antiferromagnetic-vortex dynamics driven by spin polarized current in thin discs

Generation of current vortex by spin current in Rashba systems

Employing unbiased large-scale time-dependent density-matrix renormalization-group simulations, we demonstrate the generation of a charge-current vortex via spin injection in the Rashba system. The spin current is polarized perpendicular to the system plane and injected from an attached antiferromagnetic spin chain. We discuss the conversion between spin and orbital angular momentum in the current vortex that occurs because of the conservation of the total angular momentum and the spin-orbit interaction. This is in contrast to the spin Hall effect, in which the angular-momentum conservation is…

From collinear to vortex magnetic structures in Mn corrals on Pt(111)

We study the magnetic properties of small Mn ring shaped clusters on a Pt(111) surface in the framework of density functional theory. We find that the Mn atoms possess large magnetic moments, of the order of 4uB/atom, and have dominating antiferromagnetic interatomic exchange interactions. A quantum confinement effect within the ring like clusters was found, indicating that even very small clusters can be seen as quantum corrals. The antiferromagnetic exchange couplings lead to collinear magnetic arrangements in simple corrals, as well as complex non-collinear ordering, as vortex-like structur…

Fast Vortex Oscillations in a Ferrimagnetic Disk near the Angular Momentum Compensation Point

We theoretically study the oscillatory dynamics of a vortex core in a ferrimagnetic disk near its angular momentum compensation point, where the spin density vanishes but the magnetization is finite. Due to the finite magnetostatic energy, a ferrimagnetic disk of suitable geometry can support a vortex as a ground state similar to a ferromagnetic disk. In the vicinity of the angular momentum compensation point, the dynamics of the vortex resemble those of an antiferromagnetic vortex, which is described by equations of motion analogous to Newton's second law for the motion of particles. Owing to…

Current-driven nucleation and propagation of antiferromagnetic skyrmionium

We present a theoretical study on nucleation and propagation of antiferromagnetic skyrmionium induced by spin current injection. A skyrmionium, also known as 2π skyrmion, is a vortex-like magnetic structure characterized by a topological charge, the so-called skyrmion number, being zero. We find that an antiferromagnetic skyrmionium can be generated via a local injection of spin current with toroidal distribution. A spatially uniform spin current is then demonstrated to induce a propagation of the skyrmionium. We derive an expression for the skyrmionium velocity based on a collective-coordinat…

$\mathbb{Z}_2$ 旋涡晶体在四面体反铁磁体中的形成：分数电荷与拓扑磁子

$\mathbb{Z}_2$ Vortex Crystals in Tetrahedral Antiferromagnets: Fractional Charges and Topological Magnons

研究在四面体反铁磁体中发现$\mathbb{Z}_2$旋涡晶体，揭示其分数电荷与拓扑磁子特性。

Field-induced spin reorientation transitions in antiferromagnetic ring-shaped spin chains

Easy axis antiferromagnets are robust against external magnetic fields of moderate strength. Spin reorientations in strong fields can provide an insight into more subtle properties of antiferromagnetic materials, which are often hidden by their high ground state symmetry. Here, we investigate theoretically effects of curvature in ring-shaped antiferromagnetic achiral anisotropic spin chains in strong magnetic fields. We identify the geometry-governed helimagnetic phase transition above the spin-flop field between vortex and onion states. The curvature-induced Dzyaloshinskii-Moriya interaction …

磁涡旋对中自旋波的可操控电流驱动发射

Steerable current-driven emission of spin waves in magnetic vortex pairs

该研究利用时间分辨扫描透射X射线显微镜和微磁学模拟，证明在反铁磁耦合磁涡旋中电流驱动的奥斯特场可高效激发自旋波，并通过磁致伸缩材料实现传播方向的可操控调节，为磁振子器件中自旋波的产生与控制提供了新方法。

VSe2纳米管中直径控制的高阶涡旋态与磁振子杂化

Diameter-Controlled High-Order Vortex States and Magnon Hybridization in VSe2 Nanotubes

本研究通过密度泛函理论与Heisenberg建模，揭示VSe2纳米管中直径控制的高阶涡旋态（如3φ态）可实现传统系统禁止的轨道角动量选择定则下的磁振子杂化，为高OAM磁振子产生及自旋波信息传输提供无平台方案。

Vortex Dynamics: Quantum versus Classical Regimes

For many years the classical Hall-Vinen-Iordanski (HVI) equation has been used to analyse vortex dynamics in superfluids. Here we discuss the extension of the theory of vortex dynamics to the quantum regime, in which the characteristic vortex frequency is higher than the temperature. At the same time we justify, in the low-frequency classical regime, the use of the HVI equation, provided an inertial mass term and a noise fluctuation term are added to it. The crossover to the quantum regime is discussed, and an intuitive picture is given of the vortex dynamics, which in general is described by …