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521 result(s) for "magnetic soliton"
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Voltage-controlled magnetic solitons motion in an anisotropic ferromagnetic nanowire
The precise manipulation of magnetic solitons remains a challenge and is considered a crucial process in magnetic storage. In this paper, we investigate the control of velocity and spatial manipulation of magnetic solitons using the voltage-controlled magnetic anisotropy effect. A long-wave model, known as the generalized derivative nonlinear Schrödinger (GDNLS) equation, is developed to describe the dynamics of magnetic solitons in an anisotropic ferromagnetic nanowire. By constructing the Lax pair for the GDNLS equation, we obtain the exact solutions including magnetic dark solitons, anti-dark solitons, and periodic solutions. Moreover, we propose two approaches to manipulate magnetic solitons: direct voltage application and inhomogeneous insulation layer design. Numerically results show the direct modulation of soliton velocity by a constant voltage, while time-varying voltage induces periodic oscillations. Investigation of Gaussian-type defects reveals soliton being trapped beyond a critical defect depth. These results provide a theoretical basis for future applications in magnetic soliton-based memory devices.
Phase diagram, stability and magnetic properties of nonlinear excitations in spinor Bose-Einstein condensates
We present the phase diagram, the underlying stability and magnetic properties as well as the dynamics of nonlinear solitary wave excitations arising in the distinct phases of a harmonically confined spinor F = 1 Bose-Einstein condensate. Particularly, it is found that nonlinear excitations in the form of dark-dark-bright solitons exist in the antiferromagnetic and in the easy-axis phase of a spinor gas, being generally unstable in the former while possessing stability intervals in the latter phase. Dark-bright-bright solitons can be realized in the polar and the easy-plane phases as unstable and stable configurations respectively; the latter phase can also feature stable dark-dark-dark solitons. Importantly, the persistence of these types of states upon transitioning, by means of tuning the quadratic Zeeman coefficient from one phase to the other is unravelled. Additionally, the spin-mixing dynamics of stable and unstable matter waves is analyzed, revealing among others the coherent evolution of magnetic dark-bright, nematic dark-bright-bright and dark-dark-dark solitons. Moreover, for the unstable cases unmagnetized or magnetic droplet-like configurations and spin-waves consisting of regular and magnetic solitons are seen to dynamically emerge remaining thereafter robust while propagating for extremely large evolution times. Interestingly, exposing spinorial solitons to finite temperatures, their anti-damping in trap oscillation is showcased. It is found that the latter is suppressed for stronger bright soliton component 'fillings'. Our investigations pave the wave for a systematic production and analysis involving spin transfer processes of such waveforms which have been recently realized in ultracold experiments.
Topological spin/structure couplings in layered chiral magnet Cr1/3TaS2: The discovery of spiral magnetic superstructure
SignificanceMagnets in which chirality of crystal lattice gives rise to noncollinear spin orders are ideal playgrounds for studies of novel physical phenomena originating from the nontrivial topology of magnetic textures. Most studies have been focused on homochiral materials, while topological magnetic states of heterochiral magnets have rarely been explored. Here, we report a layered chiral helimagnet with highly tunable topological heterochiral states. Tuning the chiral domain density, we have observed a topological magnetic texture that has the form of a spiral unfolding in the radial direction. In weak in-plane fields, this spiral magnetic superstructure transforms into a nonspiral array of concentric rings. Our results open a horizon for studies of tunable topological magnetic textures. Chiral magnets have recently emerged as hosts for topological spin textures and related transport phenomena, which can find use in next-generation spintronic devices. The coupling between structural chirality and noncollinear magnetism is crucial for the stabilization of complex spin structures such as magnetic skyrmions. Most studies have been focused on the physical properties in homochiral states favored by crystal growth and the absence of long-ranged interactions between domains of opposite chirality. Therefore, effects of the high density of chiral domains and domain boundaries on magnetic states have been rarely explored so far. Herein, we report layered heterochiral Cr1/3TaS2, exhibiting numerous chiral domains forming topological defects and a nanometer-scale helimagnetic order interlocked with the structural chirality. Tuning the chiral domain density, we discovered a macroscopic topological magnetic texture inside each chiral domain that has an appearance of a spiral magnetic superstructure composed of quasiperiodic Néel domain walls. The spirality of this object can have either sign and is decoupled from the structural chirality. In weak, in-plane magnetic fields, it transforms into a nonspiral array of concentric ring domains. Numerical simulations suggest that this magnetic superstructure is stabilized by strains in the heterochiral state favoring noncollinear spins. Our results unveil topological structure/spin couplings in a wide range of different length scales and highly tunable spin textures in heterochiral magnets.
Fe Doping-Induced Magnetic Solitons in CrNb3S6
Helicoidal ferromagnetic materials' spin spirals in the magnetic soliton lattice provide excellent computer storage capability. In this study, we successfully prepared FexCr1−xNb3S6 powders using powder metallurgy. Through elemental analysis and x-ray diffraction analysis, the consistent distribution of Fe elements throughout the powder and the solid solution of Fe into Cr atom occupancy were confirmed . The magnetization response to a magnetic field exhibited a complex behavior, as the gradual replacement of Cr with Fe transformed the material from ferromagnetism to antiferromagnetism. Additionally, step-like magnetic transitions in FeNb3S6 powders were discovered . To further explore these phenomena, we prepared FeNb3S6 single crystals using chemical vapor transport. The single crystal analysis revealed a highly distinct pattern of more stable steps (30–120 K) in the dM/dH curve, indicating a change in spin spirals within the magnetic solitons due to minor magnetic disturbances and a strong anisotropy energy. The replacement of Cr by Fe leads to a rearrangement of the direction of magnetic moments, resulting in the disappearance and emergence of the magnetic solitons. These findings contribute to the development of a novel material system for spintronic memory devices, harnessing a chiral magnetic structure.
Topological spin/structure couplings in layered chiral magnet Cr 1/3 TaS 2 : The discovery of spiral magnetic superstructure
Magnets in which chirality of crystal lattice gives rise to noncollinear spin orders are ideal playgrounds for studies of novel physical phenomena originating from the nontrivial topology of magnetic textures. Most studies have been focused on homochiral materials, while topological magnetic states of heterochiral magnets have rarely been explored. Here, we report a layered chiral helimagnet with highly tunable topological heterochiral states. Tuning the chiral domain density, we have observed a topological magnetic texture that has the form of a spiral unfolding in the radial direction. In weak in-plane fields, this spiral magnetic superstructure transforms into a nonspiral array of concentric rings. Our results open a horizon for studies of tunable topological magnetic textures. Chiral magnets have recently emerged as hosts for topological spin textures and related transport phenomena, which can find use in next-generation spintronic devices. The coupling between structural chirality and noncollinear magnetism is crucial for the stabilization of complex spin structures such as magnetic skyrmions. Most studies have been focused on the physical properties in homochiral states favored by crystal growth and the absence of long-ranged interactions between domains of opposite chirality. Therefore, effects of the high density of chiral domains and domain boundaries on magnetic states have been rarely explored so far. Herein, we report layered heterochiral Cr 1/3 TaS 2 , exhibiting numerous chiral domains forming topological defects and a nanometer-scale helimagnetic order interlocked with the structural chirality. Tuning the chiral domain density, we discovered a macroscopic topological magnetic texture inside each chiral domain that has an appearance of a spiral magnetic superstructure composed of quasiperiodic Néel domain walls. The spirality of this object can have either sign and is decoupled from the structural chirality. In weak, in-plane magnetic fields, it transforms into a nonspiral array of concentric ring domains. Numerical simulations suggest that this magnetic superstructure is stabilized by strains in the heterochiral state favoring noncollinear spins. Our results unveil topological structure/spin couplings in a wide range of different length scales and highly tunable spin textures in heterochiral magnets.
Investigation of the propagation of coupled laser pulses in a plasma
In this paper, the propagation of an electromagnetic pulse due to the interaction of laser pulse and plasma was investigated using a set of fluid relativistic equations and Maxwell’s equations in an unmagnetized collisionless common plasma. Using the multiple scale perturbation approach, the dispersion relation and the group velocity were derived, and finally it was shown that the evaluation of the components of vector potential is governed by two coupled-nonlinear Schrödinger (NLS) equations. It should be noted that using the relations of the phase and group velocities we understated that they are independent from plasma parameters. Then, using analytical methods, the solutions of the amplitude of the coupled Schrodinger equations for both components of the vector potential were obtained. Analytically, the modulation instability conditions in terms of plasma parameters have been investigated. Finally, by plotting the figures, the modulation stability and instability regions are numerically studied.
Current-driven magnetization reversal dynamics and breather-like EM soliton propagation in biaxial anisotropic weak ferromagnetic nanowire
We investigate the effect of spin torque on the switching dynamics of magnetic solitons in a weak ferromagnetic nanowire under the influence of an electromagnetic wave (EMW). The magnetization dynamics of the current-driven ferromagnetic nanowire and the EMW propagation is governed by the celebrated Landau-Lifshitz-Gilbert (LLG) vector equation and the Maxwell’s equations, respectively. We recast the set of LLG and Maxwell equations onto the extended derivative nonlinear Schr o ¨ dinger (EDNLS) equation. We employ the nonlinear perturbation analysis along the lines of Kodama and Ablowitz and analyze the interplay of the Dzyaloshinskii-Moriya interaction (DMI) along with the spin transfer torque on the magnetization reversal dynamics by solving the associated evolution equations for the soliton parameters. We also demonstrate the spin-polarized current triggers an ultrafast switching of EM solitons in the ferromagnetic nanowire in the range of 0.58 - 0.12 n s , and the Gilbert damping supports the EM soliton switching to sustain indefinitely. We invoke the Jacobi elliptic function method to explore the propagation of breather-like solitonic localized modes along the ferromagnetic nanowire.
Optimality of linear vacancy defect for skyrmion nucleation
Magnetic skyrmions offer a pathway to ultra-dense, low-power memory, but writing them efficiently remains a challenge. Using atomistic spin simulations and minimum energy path calculations in a PdFe/Ir(111) film, we show that deliberately placing linear chains of four atomic vacancies cuts the skyrmion nucleation barrier nearly in half-down to 44.7 meV at 3.75 T-compared to 85 meV in a pristine track. Linear defects excel because they remove high-energy core regions during skyrmion creation while minimally disturbing its outer negative energy halo during depinning. This geometry-driven effect relies only on generic energy density profiles, making it broadly applicable to all skyrmion-hosting materials.
Observation of the Chiral Soliton Lattice above Room Temperature
Magnetic chiral soliton lattices (CSLs) emerge from the helical phase in chiral magnets when magnetic fields are applied perpendicular to the helical propagation vector, and they show great promise for next‐generation magnetic memory applications. These one‐dimensional structures are previously observed at low temperatures in samples with uniaxial symmetry. Here, it is found that in‐plane fields are the key to stabilizing the CSL in cubic Co8Zn10Mn2 over the entire temperature range from 15 K to below the Curie temperature (365 K). Using small‐angle resonant elastic X‐ray scattering, it is observed that the CSL is stabilized with an arbitrary in‐plane propagation vector, while its thin plate geometry plays a deciding role in the soliton wavelength as a function of applied field. This work paves the way for high temperature, real world applications of soliton physics in future magnetic memory devices. The chiral soliton lattice (CSL) state is demonstrated at temperatures of up to 355 K in Co8Zn10Mn2. In contrast to the low‐temperature CSL material Cr1/3NbS2, the CSL state in Co8Zn10Mn2 is not governed by crystallographic constraints. Instead, it is controlled by in‐plane fields, enabling their device integration and opening the door to room‐temperature solitonic applications.
Temperature- and field angular-dependent helical spin period characterized by magnetic dynamics in a chiral helimagnet MnNb3S6
The chiral magnets with topological spin textures provide a rare platform to explore topology and magnetism for potential application implementation. Here, we study the magnetic dynamics of several spin configurations on the monoaxial chiral magnetic crystal MnNb 3 S 6 via broadband ferromagnetic resonance (FMR) technique at cryogenic temperature. In the high-field forced ferromagnetic state (FFM) regime, the obtained frequency f vs. resonance field H res dispersion curve follows the well-known Kittel formula for a single FFM, while in the low-field chiral magnetic soliton lattice (CSL) regime, the dependence of H res on magnetic field angle can be well-described by our modified Kittel formula including the mixture of a helical spin segment and the FFM phase. Furthermore, compared with the sophisticated Lorentz micrograph technique, the observed magnetic dynamics corresponding to different spin configurations allow us to obtain temperature- and field-dependent proportion of helical spin texture and helical spin period ratio L ( H )/ L (0) via our modified Kittel formula. Our results demonstrated that field- and temperature-dependent nontrivial magnetic structures and corresponding distinct spin dynamics in chiral magnets can be an alternative and efficient approach to uncovering and controlling nontrivial topological magnetic dynamics.