Magnetic skyrmions are regarded as promising information candidates in future spintronic devices, which have been investigated theoretically and experimentally in isotropic system. Recently, the sta- bilization of antiskyrmions in the presence of anisotropic Dzyaloshinskii-Moriya interaction and its dynamics driven by current have been investigated. Here, we report the antiskyrmion motion with the combined action of the in-plane magnetic field and microwave electric fields. The in-plane mag- netic field breaks the rotation symmetry of the antiskyrmion, and perpendicular microwave electric field induces the pumping of magnetic anisotropy, leading to antiskyrmion breathing mode. With above two effects, the antiskyrmion propagates with a desired trajectory. Antiskyrmion propagation velocity depends on the frequency, amplitude of anisotropy pumping, and damping constant as well as strength of in-plane field, which reaches the maximum value when the frequency of microwave electric field is in consist with the resonance frequency of antiskyrmion. Moreover, we show that the antiskyrmion propagation depends on the direction of magnetic field, where the antiskyrmion Hall angle can be suppressed or enhanced. At a critical direction of magnetic field, the Hall angle is zero. Our results introduce a possible application of antiskyrmion in antiskyrmion-based spintronic devices with lower energy consumption.
Magnetic skyrmions are nanoscale spin whirlpools that promise breakthroughs in future spintronic applications. Controlled generation of magnetic skyrmions by electric current is crucial for this purpose. While previous studies have demonstrated this operation, the topological charge of the generated skyrmions is determined by the direction of the external magnetic fields, thus is fixed. Here, we report the current-induced skyrmions creation in a chiral magnet FeGe nanostructure by using the \emph{in-situ} Lorentz transmission electron microscopy. We show that magnetic skyrmions or antiskyrmion…
Magnetic skyrmions and their anti-particles, the antiskyrmions, are stable magnetic solitons existing down to the nanometer scale. Their stability and size as well as the possibility to propel them by, e.g., electric currents make them promising candidates for the use in memory devices, such as racetrack memories. Skyrmions and antiskyrmions share those same advantages individually, but may annihilate each other when they coexist in the same device. Yet, combining them to represent logical bits of 0 (skyrmion) and 1 (antiskyrmion) in one device opens new possibilities to create new types of de…
Magnetic skyrmions can be considered as topologically protected localized vortex-like spin textures. Due to their stability, their small size, and the possibility to move them by low electric currents they are promising candidates for spintronic devices. Without violating topological protection, it is possible to create skyrmion-antiskyrmion pairs, as long as the total charge remains unchanged. We derive a skyrmion equation of motion which reveals how spin-polarized charge currents create skyrmion-antiskyrmion pairs. It allows to identify general prerequisites for the pair creation process. We…
Magnetic skyrmions are particle-like topological excitations recently discovered in chiral magnets. Their small size, topological protection and the ease with which they can be manipulated by electric currents generated much interest in using skyrmions for information storage and processing. Recently, it was suggested that skyrmions with additional degrees of freedom can exist in magnetically frustrated materials. Here, we show that dynamics of skyrmions and antiskyrmions in nanostripes of frustrated magnets is strongly affected by complex spin states formed at the stripe edges. These states c…
The skyrmions generated by frustration in centrosymmetric structures host extra internal degrees of freedom: vorticity and helicity, resulting in distinctive properties and potential functionality, which are not shared by the skyrmions stemming from the Dzyaloshinskii-Moriya interaction in noncentrosymmetric structures. The present work indicates that the magnetism-driven electric polarization carried by skyrmions provides a direct handle for tuning helicity. Especially for the in-plane magnetized skyrmions, the helicity can be continuously rotated and exactly picked by applying an external el…
Near-field microwave imaging of inhomogeneous K$_x$Fe$_y$Se$_2$: separation of topographic and electric features
克服表面粗糙度的影响是现代扫描微波显微镜的重要内容。在这里，我们报告微波电导率成像相分离的铁硫属化物K $_x$ Fe $_y$ Se $_2$（$x=0.8$，$y=1.6$ - $2$），其中电导率引起的对比度是区分从地形引起的对比度使用扫描隧道显微镜和扫描微波显微镜（STM-SMM）的组合。在恒电流（CC）和恒$Q$（CQ）两种扫描模式下，我们观察到了由金属相和半导体相的介观相分离引起的局域电性质的特征调制。特别是，CQ扫描是有用的，因为我们得到一个定性的图像，其中的地形对比度在很大程度上被消除，而不会降低空间分辨率。
We theoretically reveal that pure eigenmodes of an isolated magnetic skyrmion embedded in a ferromagnetic environment can be selectively activated using microwave electric fields without exciting gigantic ferromagnetic resonances, in contrast to conventional methods using microwave magnetic fields. We also demonstrate that this selective activation of a skyrmion can efficiently drive its translational motion in a ferromagnetic nanotrack under application of an external magnetic field inclined from the normal direction. We find that a mode with combined breathing and rotational oscillations ind…
Surface Acoustic Waves (SAW) have been utilized to investigate the properties of a two-dimensional electron system, subjected to a perpendicular magnetic field and monochromatic microwave radiation, in the regime where the so-called microwave-induced zero-resistance states form. Contrary to conventional magneto-transport in Hall bar and van der Pauw geometries, the collimated SAW beam probes only the bulk of the electronic system exposed to this wave. Clear signatures appear in the SAW propagation velocity corroborating that neither contacts, nor sample edges are a root source for their emerge…
We theoretically show that a temporally oscillating spin-driven electromotive force or voltage with a large DC component can be generated by exciting microwave-active spin-wave modes of a skyrmion crystal confined in a quasi two-dimensional magnet under a tilted magnetic field. The DC component and the AC amplitude of the oscillating electric voltage is significantly enhanced when the microwave frequency is tuned to an eigenfrequency of the peculiar spin-wave modes of the skyrmion crystal called ``rotation modes" and ``breathing mode", whereas the sign of the DC component depends on the microw…
The nuclear spin state of a phosphorus donor ($^{31}$P) in isotopically enriched silicon-28 is an excellent host to store quantum information in the solid state. The spin's insensitivity to electric fields yields a solid-state qubit with record coherence times, but also renders coupling to other quantum systems very challenging. Here, we describe how to generate a strong electric dipole ($>100$ Debye) at microwave frequencies for the nuclear spin. This is achieved by applying a magnetic drive to the spin of the donor-bound electron, while simultaneously controlling its charge state with electr…
We show that a controllable dc magnetization is accumulated in a junction comprising a quantum dot coupled to non-magnetic reservoirs if the junction is subjected to a time-dependent spin-orbit interaction. The latter is induced by an ac electric field generated by microwave irradiation of the gated junction. The magnetization is caused by inelastic spin-flip scattering of electrons that tunnel through the junction, and depends on the polarization of the electric field: a circularly polarized field leads to the maximal effect, while there is no effect in a linearly polarized field. Furthermore…
Electron spins confined in quantum dots are an attractive system to realize high-fidelity qubits owing to their long coherence time. With the prolonged spin coherence time, however, the control fidelity can be limited by systematic errors rather than decoherence, making characterization and suppression of their influence crucial for further improvement. Here we report that the control fidelity of Si/SiGe spin qubits can be limited by the microwave-induced frequency shift of electric dipole spin resonance and it can be improved by optimization of control pulses. As we increase the control micro…
Magnetotransport in a two-dimensional electron system in dc electric fields
本文报道了在弱磁场和直流激励下高迁移率二维电子系统的非平衡输运测量。由Yang { \em et al}首先观察到的直流感应磁振荡的详细研究，揭示了一个谐振条件，是定性不同，从先前报道的。此外，我们观察到显着减少电阻引起的弱直流电场在政权的分离朗道水平。这些结果表明，在直流驱动和微波驱动系统的传输现象的相似性，并正在进行的实验研究预测淬火微波诱导的零电阻状态的直流电流具有重要意义。
We report on the generic classical electric circuit modeling that describes standard single-tone microwave optomechanics. Based on a parallel RLC circuit in which a mechanical oscillator acts as a movable capacitor, derivations of analytical expressions are presented, including key features such as the back-action force, the input-output expressions, and the spectral densities associated, all in the classical regime. These expressions coincide with the standard quantum treatment performed in optomechanics when the occupation number of both cavity and mechanical oscillator are large. Besides, t…
Hole-spins localized in semiconductor structures, such as quantum dots or defects, serve to the realization of efficient gate-tunable solid-state quantum bits. Here we study two electrically driven spin $3/2$ holes coupled to the electromagnetic field of a microwave cavity. We show that the interplay between the non-Abelian Berry phases generated by local time-dependent electrical fields and the shared cavity photons allows for fast manipulation, detection, and long-range entanglement of the hole-spin qubits in the absence of any external magnetic field. Owing to its geometrical structure, suc…
We propose a theoretical model of magnetization switching in a ferromagnetic multilayer by both electric current and microwaves. The electric current gives a spin transfer torque on the magnetization, while the microwaves induce a precession of the magnetization around the initial state. Based on numerical simulation of the Landau-Lifshitz-Gilbert (LLG) equation, it is found that the switching current is significantly reduced compared with the switching caused solely by the spin transfer torque when the microwave frequency is in a certain range. We develop a theory of switching from the LLG eq…
We study the effects of electrostatic gating on the magnetization auto-oscillations induced by the local injection of electric current into a ferromagnet/heavy metal bilayer. We find that the characteristic currents required for the excitation, the intensity and the spectral characteristics of the generated dynamical states can be tuned by the voltage applied to the metallic gate separated from the bilayer by a thin insulating layer. We show that the effect of electrostatic gating becomes enhanced in the strongly nonlinear oscillation regime at sufficiently large driving currents. Analysis sho…
