Spin waves in magnetic nanotubes with helical equilibrium magnetization
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Nicolas Vidal-Silva said…
Hi, nice work, congrats. Which is the substantial difference between the general helical case with the vortex case? How are the spin waves modified (non-reciprocity, dispersion, and so on) when comparing both cases?
Hi Nicolas. Thanks for your reply. Vortex and helical magnetic configurations are both equilibrium states of the nanotube. However, the helical state requires applying a longitudinal field to be stabilized, besides the circular magnetic field required to stabilize the vortex state. In this study, non-reciprocities are measured, as stated in the equation referred to as frequency asymmetry. This frequency asymmetry is calculated for the dispersion relation of the fundamental and first modes of the nanotube's spin-waves. In both cases, the dispersion relation is asymmetric. However, in the helical state, the interest is to study this dispersion asymmetries not only when the longitudinal field is zero (vortex case), but also when it differs from zero (helical case).
Anonymous said…
Help me to understand the proposed experiment with CPWs. How does it works? Thanks
Hi. The proposed experimental device consists of a nanotube with an electric conductor wire as a core, and at its end, an electric current is applied to generate a magnetic field. This field has a circular magnetic field as its axial component and a longitudinal field as its z-axis component. For the critical values of this applied field, it is possible to stabilize the helical equilibrium state. Besides, two waveguides are placed under the nanotube, separated a distance s one each other. The waveguide 1 allows us to introduce a slight perturbation by applying an rf current in this coplanar waveguide 1. Subsequently, the perturbed magnetic configuration of the spin waves in the nanotube is obtained by measuring the voltage at the coplanar waveguide 2. One can perform the procedure as mentioned earlier, applying current in the complanar waveguide 2, and measure the voltage in the coplanar waveguide 1. With the mentioned measures, the asymmetries presented in the analytical model are studied through the comparison between the frequencies for reciprocal wave vectors.
Nicolas vidal-Silva said…
Thank you for your reply Monica. Again, nice work!
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