Using micromagnetic simulation, we show that in-plane uniaxial magnetic anisotropy (IPUA) can be used to obtain FAN-OUT, AND and OR gates in an array of coupled disks with magnetic vortex configuration. First, we studied the influence of the direction of application of the IPUA on the energy transfer time (τ) between two identical coupled nanodisks. We found that when the direction of the IPUA is along the x axis the magnetic interaction increases, allowing shorter values of τ, while the IPUA along the y direction has the opposite effect. The magnetic interactions between the nanodisks along x and y directions (the coupling integrals) as a function of the uniaxial anisotropy constant (K σ ) were obtained using a simple dipolar model. Next, we demonstrated that choosing a suitable direction of application of the IPUA, it is possible to create several different logic gates with a single array of coupled nanodisks
In this article we investigate the induction of a surface anisotropy due to the displacement of the vortex core in a cylindrical nanostructure. In fact, the effect of the displacement of the vortex core in the dipolar energy can be modeled simply as a surface anisotropy of the form $E_s = K_s \int_{\mathcal{S}_m} d\mathcal{S} \, (\hat{n} \cdot \hat{m})^2/2$. Moreover, the surface anisotropy constant $K_s$ is proportional to the cylinder in-plane demagnetizing factor in the direction of the core deviation, $N_y(L/R)$, i.e., $K_s = μ_0 M_0^2 R \, N_y(L/R)$, where $R$ and $L$ are the radius and t…
Magnetic analogue of electronic gates are advantageous in many ways. There is no electron leakage, higher switching speed and more energy saving in a magnetic logic device compared to a semiconductor one. Recently, we proposed a magnetic vortex transistor and fan-out out devices based on carefully coupled magnetic vortices in isolated nanomagnetic disks. Here, we demonstrate a new type of magnetic logic gate based upon asymmetric vortex transistor by using micromagnetic simulation. Depending upon two main features (topology) of magnetic vortex, chirality and polarity, the network can behave li…
Recently discovered exotic magnetic configurations, namely magnetic solitons appearing in the presence of bulk or interfacial Dzyaloshinskii-Moriya Interaction (i-DMI), have excited scientists to explore their potential applications in emerging spintronic technologies such as race-track magnetic memory, spin logic, radio frequency nano-oscillators and sensors. Such studies are motivated by their foreseeable advantages over conventional micro-magnetic structures due to their small size, topological stability and easy spin-torque driven manipulation with much lower threshold current densities gi…
The switching of a vortex core of a single disk in an array of a multilayer system is investigated by micromagnetic simulation. We found that the perpendicular uniaxial anisotropy (PUA) decreases the frequencies of the azimuthal mode in disks with magnetic vortex configuration. We obtained a phase diagram of magnetic field intensity vs. frequency of the azimuthal mode, as a function of the value of perpendicular uniaxial anisotropy. We demonstrated that rotating magnetic fields (CW and CCW) with frequency equal to azimuthal modes can be used to switch the vortex core of single disks in a disk …
Spin waves (SWs) have been considered a promising candidate for encoding information with lower power consumption. Here, we propose the dual function SW logic gates based on the electric field controlling the SW propagation in the Fe film of Fe/BaTiO3 heterostructure with the motion of magnetic anisotropy boundary (MAB). We show micromagnetic simulations to validate the AND-OR and NAND-NOR logic gates. Our research may find a path for simplifying integrated logic circuits using such dual function SW logic gates.
Nanomagnetic logic has emerged as a potential replacement for traditional CMOS-based logic because of superior energy-efficiency. One implementation of nanomagnetic logic employs shape-anisotropic (e.g. elliptical) ferromagnets (with two stable magnetization orientations) as binary switches that rely on dipole-dipole interaction to communicate binary information. Normally, circular nanomagnets are incompatible with this approach since they lack distinct stable in-plane magnetization orientations to encode bits. However, circular magnetoelastic nanomagnets can be made bi-stable with a voltage i…
Unusual magneto-transport of YBa2Cu3O7-d films due to the interplay of anisotropy, random disorder and nanoscale periodic pinning
我们研究了一个流形的相互作用的弹性线的空间相关性的强烈影响随机和有序钉扎之间的竞争的一般问题。这是通过磁输运实验与YBa 2 Cu 3 O 7-d薄膜，包含一个周期性的涡旋钉扎阵列通过掩蔽离子照射，除了本地随机钉扎。我们观察到的强场匹配效应表明周期性钉扎的普遍存在，并表明在匹配场中每条涡旋线都束缚在人为钉扎位点上。然而，涡玻璃化转变的维度，准2D而不是通常的3D，证据减少沿涡线的涡玻璃相关性。这也支持了一个不寻常的角度依赖的磁阻，这大大不同于玻色玻璃系统。角磁阻的定量分析使我们能够将这种行为与系统各向异性的增强联系起来，这是离子辐照的附带效应。
The influence of the in-plane uniaxial anisotropy (IPUA) in the mutual energy transfer time ($τ$) between two identical coupled nanodisks was studied. Using an analytical dipolar model we obtained the interactions between the disks along x and y directions (the coupling integrals) as a function of the uniaxial anisotropy constant (K$_σ$) and the distance. We find that the IPUA increases the interaction between the disks allowing shorter energy transfer times. For our range of K$_σ$ values we get a drop in the values of $τ$ of up to about 70$\%$. From the lagrangian of the system we obtained th…
The influence of a strain-induced uniaxial magnetoelastic anisotropy on the magnetic vortex core dynamics in microstructured magnetostrictive Co$_{40}$Fe$_{40}$B$_{20}$ elements was investigated with time-resolved scanning transmission x-ray microscopy. The measurements revealed a monotonically decreasing eigenfrequency of the vortex core gyration with the increasing magnetoelastic anisotropy, which follows closely the predictions from micromagnetic modeling.
We report on experimental and computational investigations of the domain structure of ~0.2 x 0.2 x 8 μm single-crystal Ni nanowires (NWs). The Ni NWs were grown by a thermal chemical vapor deposition technique that results in highly-oriented single-crystal structures on amorphous SiOx coated Si substrates. Magnetoresistance measurements of the Ni NWs suggest the average magnetization points largely off the NW long axis at zero field. X-ray photoemission electron microscopy images show a well-defined periodic magnetization pattern along the surface of the nanowires with a period of λ = 250 nm. …
On the shape of vortices for a rotating Bose Einstein condensate
对于置于旋转阱中的玻色-爱因斯坦凝聚体，我们研究了Aftalion-Riviere Phys. Rev. A 64，043611（2001）中推导的涡旋线的简化能量，以便根据凝聚体的旋转速度和伸长来确定涡旋线的形状。能量反映了考虑到阱的各向异性而需要最小化的涡旋长度与沿着z轴推动涡旋的旋转项之间的竞争。我们证明，如果冷凝物的形状的煎饼，涡保持直线沿z轴，而在雪茄的情况下，涡是弯曲的。
We study spin-wave excitations in a circular ferromagnetic nanodot in different inhomogeneous, topologically non-trivial magnetization states, specifically, vortex and skyrmion states. Gradual change in the strength of the out-of-plane magnetic anisotropy and the Dzyaloshinskii-Moriya exchange interaction leads to continuous phase transitions between different stable magnetic configurations and allows for mapping of dynamic spin modes in and between the vortex, Bloch-type skyrmion and Néel-type skyrmion states. Our study elucidates the connections between gyrotropic modes, azimuthal spin waves…
Magnetic skyrmions are exciting candidates for energy-efficient computing due to their non-volatility, detectability,and mobility. A recent proposal within the paradigm of reversible computing enables large-scale circuits composed ofdirectly-cascaded skyrmion logic gates, but it is limited by the manufacturing difficulty and energy costs associated withthe use of notches for skyrmion synchronization. To overcome these challenges, we therefore propose a skyrmion logicsynchronized via modulation of voltage-controlled magnetic anisotropy (VCMA). In addition to demonstrating theprinciple of VCMA s…
The renormalization group equations describing a finite 2DXY system with fourfold anisotropy are solved in two steps, in order to study the magnetic transition to paramagnetism in an ultrathin film. First, the equations are linearized near the critical coupling $K=J/k_BT=2/π$. An exact solution of the linearized equations confirms that a finite-size Kosterlitz-Thouless (KT) transition occurs in the presence of weak fourfold anisotropy, and that an Ising transition occurs for strong anisotropy. The behaviour of a given system is determined by the product of an anisotropy parameter and the logar…
Directional vortex pinning at microwave frequency in YBa$_{2}$Cu$_3$O$_{7-x}$ thin films with BaZrO$_3$ nanorods
研究了用脉冲激光烧蚀法从含5%（摩尔分数）BaZrO $_3$的靶上生长的YBaPDMATHABMM CuPDMATHABMN O $_{7-x}$薄膜的各向异性和定向钉扎效应. BaZrO $_3$夹杂物自组装得到沿c轴取向的纳米棒，从而为涡旋钉扎提供了优先方向。涡旋响应的方向性研究在高交流频率与复杂的微波响应在48 GHz，作为一个功能的应用领域和领域和c轴之间的角度$θ$。复杂的微波响应不表现出任何角度缩放，这表明YBa $_2$ Cu $_3$ O $_{7-x}$的结构各向异性的补充，至少另一个优选的取向。钉扎参数$r$显示定向钉扎的证据，在围绕c轴的宽范围的角度中有效（因此归因于BZO纳米柱）。
Cylindrical magnetic nanowires with large transversal magnetocrystalline anisotropy have been shown to sustain non-trivial magnetic configurations resulting from the interplay of spatial confinement, exchange, and anisotropies. Exploiting these peculiar 3D spin configurations and their solitonic inhomogeneities are prospected to improve magnetization switching in future spintronics, such as power-saving magnetic memory and logic applications. Here we employ holographic vector field electron tomography to reconstruct the remanent magnetic states in CoNi nanowires with 10 nm resolution in 3D, wi…
Reduced vortex descriptors linking polycrystallinity in magnetic nanoparticles with polarized magnetic small-angle neutron scattering
Max Planck Institute for the Structure and Dynamics of Matter（马克斯·普朗克物质结构与动力学研究所）；Center for Free-Electron Laser Science（自由电子激光科学中心）；Ghent University（根特大学）；University of Luxembourg（卢森堡大学）；Institute for Advanced Studies, University of Luxembourg（卢森堡大学高等研究院）
It is well known that azimuthal spin wave modes of magnetic vortex state in permalloy nanodisks have circular symmetry. Intuitively, magnetic materials having magnetocrystalline anisotropy is not compatible with the circular symmetry of the azimuthal modes. In this article, however, we report cubic azimuthal modes in heterogeneous nanodisks consisting of a permalloy core and a Fe shell. The fourfold symmetry of azimuthal modes is due to the exchange, and magneto-static, interactions between the permalloy core and the Fe shell. In comparison to results of circular azimuthal mode, the vortex swi…
