RESUMEN
The transition to the third dimension enables the creation of spintronic nanodevices with significantly enhanced functionality compared to traditional 2D magnetic applications. In this study, we extend common two-dimensional magnetic vortex configurations, which are known for their efficient dynamical response to external stimuli without a bias magnetic field, into the third dimension. This extension results in a substantial increase in vortex frequency, reaching up to 5 GHz, compared to the typical sub-GHz range observed in planar vortex oscillators. A systematic study reveals a complex pattern of vortex excitation modes, explaining the decrease in the lowest gyrotropic mode frequency, the inversion of vortex mode intensities, and the nontrivial spatial distribution of vortex dynamical magnetization noted in previous research. These phenomena enable the optimization of both oscillation frequency and frequency reproducibility, minimizing the impact of uncontrolled size variations in those magnetic nanodevices.
RESUMEN
In this work high-frequency magnetization dynamics and statics of artificial spin-ice lattices with different geometric nanostructure array configurations are studied where the individual nanostructures are composed of ferromagnetic/non-magnetic/ferromagnetic trilayers with different non-magnetic thicknesses. These thickness variations enable additional control over the magnetic interactions within the spin-ice lattice that directly impacts the resulting magnetization dynamics and the associated magnonic modes. Specifically the geometric arrangements studied are square, kagome and trigonal spin ice configurations, where the individual lithographically patterned nanomagnets (NMs) are trilayers, made up of two magnetic layers ofNi81Fe19of 30 nm and 70 nm thickness respectively, separated by a non-magnetic copper layer of either 2 nm or 40 nm. We show that coupling via the magnetostatic interactions between the ferromagnetic layers of the NMs within square, kagome and trigonal spin-ice lattices offers fine-control over magnetization states and magnetic resonant modes. In particular, the kagome and trigonal lattices allow tuning of an additional mode and the spacing between multiple resonance modes, increasing functionality beyond square lattices. These results demonstrate the ability to move beyond quasi-2D single magnetic layer nanomagnetics via control of the vertical interlayer interactions in spin ice arrays. This additional control enables multi-mode magnonic programmability of the resonance spectra, which has potential for magnetic metamaterials for microwave or information processing applications.
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We report on a comprehensive investigation of collective spin waves in Ruderman-Kittel-Kasuya-Yosida (RKKY) interlayer-coupled Ni80Fe20(10 nm)/Ru(1.0 nm)/ Ni80Fe20(10 nm) nanowire (NW) arrays. We employed Brillouin light scattering to probe the field- and wavevector-dependences of the spin-wave frequency spectra. The acquired data were subsequently analyzed and interpreted within the framework of a microscopic Hamiltonian-based method, enabling a detailed understanding of the observed spin-wave behavior. We observed the propagation of Bloch-type collective spin waves within the arrays, characterized by distinct magnonic bandwidths that stem from the combined influence of RKKY interlayer and inter-NW dynamical dipolar interactions.
RESUMEN
The nanopatterning of Yttrium Iron Garnets (YIGs) has proven to be a non-trivial problem even with advances in modern lithography techniques due to non-compatibility with a conventional complementary metal oxide semiconductor platform. In an attempt to circumvent this problem, we demonstrate a simple and reliable method to indirectly pattern YIG films on a Gadolinium Gallium Garnet (GGG) substrate. We fabricated exchange-coupled arrays of Py dots onto the underlying YIG films using nanostencil lithography. The stray fields generated from the Py dots were used to transfer patterned magnetic information to the underlying YIG films. The static and dynamic properties of the fabricated hybrid YIG/Py dot structure and reference YIG film were characterized using the focused magneto-optic Kerr effect and by broadband ferromagnetic resonance spectroscopy. For the reference YIG film, as expected, a single field-dependent resonance mode with a narrow linewidth was observed in contrast to the splitting into three distinct resonance modes for the YIG/Py dot structure as predicted by micromagnetic simulations. We have thus shown that it is possible to utilize stray field effects from easily patternable magnetic materials for the development of future YIG-based magnonic devices.
RESUMEN
The control of localized magnetic modes has been obtained in Ni60Fe40 square lattice (600 nm) antidot arrays. This has been performed by tailoring the magnetoelastic field at the scale of the antidot primitive cell. The corresponding heterogeneous strain field distributions have been generated by a PZT substrate and enhanced by the incorporation of a supporting compliant layer. It has been highlighted by a differentiated variation of magnetic energy directly due to the local magnetoelastic field felt by each magnetic mode, probed by ferromagnetic resonance spectroscopy. A modeling, involving micromagnetic simulations (to locate the magnetic modes), full-field simulations (to evaluate the strain field distributions), and an analytical model generally dedicated to continuous film that we have extended to those magnetic modes, shows a good agreement with the experimental data. This approach is very promising to develop multichannel systems with simultaneous and differentiated controlled frequencies in magnetic devices.
RESUMEN
Ferromagnetic nanorings exhibit tunable magnetic states with unique magnetization reversal processes and dynamic behavior that can be exploited in data storage and magnonic devices. Traditionally, probing the magnetization dynamics of individual ferromagnetic nanorings and mapping the resonance modes has proved challenging. In this study, micro-focused Brillouin light scattering spectroscopy is used to directly map the spin wave modes and their intensities in nanorings as a function of ring width and applied magnetic field. Micromagnetic simulations provide further insights into the experimental observations and are in good agreement with the experimental results. These results can help in improving the understanding of spin wave confinement in single elements for magnonic devices and waveguides.
RESUMEN
This work presents the effect of large strains (up to 20%) on the behavior of magnetic nanowires (Ni80Fe20) deposited on a Kapton substrate. The multicracking phenomenon was followed by in situ tensile tests combined with atomic force microscopy measurements. These measurements show, on the one hand, a delay in crack initiation relative to the nonpatterned thin film and, on the other hand, a saturation of the length of the nanowire fragments. The latter makes it possible to retain the initial magnetic anisotropy measured after deformation by ferromagnetic resonance. In addition, the ferromagnetic resonance line profile (intensity, width) is minimally affected by the numerous cracks, which is explained by the small variation in magnetic anistropy and the low magnetostriction coefficient of Ni80Fe20.
RESUMEN
Programmability of stable magnetization configurations in a magnetic device is a highly desirable feature for a variety of applications, such as in magneto-transport and spin-wave logic. Periodic systems such as antidot lattices may exhibit programmability; however, to achieve multiple stable magnetization configurations the lattice geometry must be optimized. We consider the magnetization states in Co-antidot lattices of ≈50 nm thickness and ≈150 nm inter-antidot distance. Micromagnetic simulations were applied to investigate the magnetization states around individual antidots during the reversal process. The reversal processes predicted by micromagnetics were confirmed by experimental observations. Magnetization reversal in these antidots occurs via field driven transition between 3 elementary magnetization states - termed G, C and Q. These magnetization states can be described by vectors, and the reversal process proceeds via step-wise linear operations on these vector states. Rules governing the co-existence of the three magnetization states were empirically observed. It is shown that in an n × n antidot lattice, a variety of field switchable combinations of G, C and Q can occur, indicating programmability of the antidot lattices.
RESUMEN
Magnetic vortex that consists of an in-plane curling magnetization configuration and a needle-like core region with out-of-plane magnetization is known to be the ground state of geometrically confined submicron soft magnetic elements. Here magnetodynamics of relatively thick (50-100â nm) circular Ni80Fe20 dots were probed by broadband ferromagnetic resonance in the absence of external magnetic field. Spin excitation modes related to the thickness dependent vortex core gyrotropic dynamics were detected experimentally in the gigahertz frequency range. Both analytical theory and micromagnetic simulations revealed that these exchange dominated modes are flexure oscillations of the vortex core string with n = 0,1,2 nodes along the dot thickness. The intensity of the mode with n = 1 depends significantly on both dot thickness and diameter and in some cases is higher than the one of the uniform mode with n = 0. This opens promising perspectives in the area of spin transfer torque oscillators.