Skyrmions are promising information carriers in the next-generation storage and transmission devices. Appropriate design of the nanowire that permits the flow of skyrmions is, however, seldom studied. In this work, the geometrical and material parameters have been varied to investigate the favorable conditions for skyrmion formation and stability in a nanowire through micromagnetic simulations. It is found that the minimum planar dimensions have to be satisfied in order to stabilize a skyrmion. Furthermore, the nanowire thickness is also important for establishing a skyrmion. The temperature effect in the competition between the perpendicular magnetic anisotropy (PMA) and the Dzyaloshinskii–Moriya interaction (DMI) limits the skyrmion formation in a well-defined phase. On the other hand, fine tuning of the exchange stiffness and the Gilbert damping constant sustain a specified portion of the phase diagram that allows for skyrmion formation. Our study also indicates that the stabilized magnetization pattern is dependent on the initial skyrmion state. These results shed light on the possible configurations that are suitable for the design of skyrmionic devices.
We investigate the conditions for nanocontact spin-transfer oscillators (NC-STOs) that allow for stabilization of a skyrmion. Emphasis is made on the breathing mode, which can be regarded as a source of microwave generation. Micromagnetic simulations of NC-STOs with varying parameters have been performed, with the resulting magnetization plotted in the form of phase diagrams. It is found that control of spin wave mode in conventional STOs can be applied to skyrmion-based STOs.
Modeling of field-induced magnetization in ferromagnetic materials has been an active topic in the last dozen years, yet a dynamic treatment of distance-dependent exchange integral has been lacking. In view of that, we employ spin-lattice dynamics (SLD) simulations to study the external field effect on magnetic order of ferromagnetic iron. Our results show that an external field can increase the inflection point of the temperature. Also the model provides a better description of the effect of spin correlation in response to an external field than the mean-field theory. An external field has a more prominent effect on the long range magnetic order than on the short range counterpart. Furthermore, an external field allows the magnon dispersion curves and the uniform precession modes to exhibit magnetic order variation from their temperature dependence.
Articles you may be interested inEffect of longitudinal degree of freedom of magnetic moment in body-centered-cubic iron J. Appl. Phys. 113, 17E112 (2013); 10.1063/1.4794136 Molecular dynamics simulation on deformation mechanisms in body-centered-cubic molybdenum nanowires J. Appl. Phys. 110, 093521 (2011); 10.1063/1.3660251 Molecular dynamics simulation of delamination of a stiff, body-centered-cubic crystalline film from a compliant Si substrateThe understanding of the magnetovolume effect lacks explicit consideration of spinlattice coupling at the atomic level, despite abundant theoretical and experimental studies throughout the years. This research gap is filled by the recently developed spin-lattice dynamics technique implemented in this study, which investigates the magnetovolume effect of isotropic body-centered-cubic (BCC) iron, a topic that has previously been subject to macroscopic analysis only. This approach demonstrates the magnetic anomaly followed by the volumetric changes associated with the effect, each characterized by the corresponding field-induced inflection temperature. The temperature of the heat capacity peaks is useful in determining the temperature for retarding the atomic volume increase. Moreover, this work shows the correlation between the effects of temperature and field strength in determining the equilibrium atomic volume of a ferromagnetic material under a magnetic field. C 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx.
Molecular dynamics (MD) is a technique of atomistic simulation which has facilitated scienti¯c discovery of interactions among particles since its advent in the late 1950s. Its merit lies in incorporating statistical mechanics to allow for examination of varying atomic con¯gurations at nite temperatures. Its contributions to materials science from modeling pure metal properties to designing nanowires is also remarkable. This review paper focuses on the progress of MD in understanding the behavior of iron -in pure metal form, in alloys, and in composite nanomaterials. It also discusses the interatomic potentials and the integration algorithms used for simulating iron in the literature. Furthermore, it reveals the current progress of MD in simulating iron by exhibiting some results in the literature. Finally, the review paper brie°y mentions the development of the hardware and software tools for such large-scale computations.
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