The transition from planar to three-dimensional (3D) magnetic nanostructures represents a significant advancement in both fundamental research and practical applications, offering vast potential for next-generation technologies like ultrahigh-density storage, memory, logic, and neuromorphic computing. Despite being a relatively new field, the emergence of 3D nanomagnetism presents numerous opportunities for innovation, prompting the creation of a comprehensive roadmap by leading international researchers. This roadmap aims to facilitate collaboration and interdisciplinary dialogue to address challenges in materials science, physics, engineering, and computing. The roadmap comprises eighteen sections, roughly divided into three blocks. The first block explores the fundamentals of 3D nanomagnetism, focusing on recent trends in fabrication techniques and imaging methods crucial for understanding complex spin textures, curved surfaces, and small-scale interactions. Techniques such as two-photon lithography and focused electron beam-induced deposition enable the creation of intricate 3D architectures, while advanced imaging methods like electron holography and synchrotron x-ray tomography provide nanoscale spatial resolution for studying magnetization dynamics in three dimensions. Various 3D magnetic systems, including coupled multilayer systems, artificial spin-ice, magneto-plasmonic systems, topological spin textures, and molecular magnets are discussed. The second block introduces analytical and numerical methods for investigating 3D nanomagnetic structures and curvilinear systems, highlighting geometrically curved architectures, interconnected nanowire systems, and other complex geometries. Finite element methods are emphasized for capturing complex geometries, along with direct frequency domain solutions for addressing magnonic problems. The final block focuses on 3D magnonic crystals and networks, exploring their fundamental properties and potential applications in magnonic circuits, memory, and spintronics. Computational approaches using 3D nanomagnetic systems and complex topological textures in 3D spintronics are highlighted for their potential to enable faster and more energy-efficient computing.

Cylindrical magnetic nanowires (NWs) have gained significant interest as building-blocks of spintronics devices and magnetic sensors thanks to their geometry-tunable magnetic properties and anisotropy. While the synthesis and compositional control of NWs have seen major improvements in recent years, considerable challenges remain for the characterization of local magnetic features at the nanoscale. Here, we demonstrate non-perturbative field distribution mapping and minimally invasive magnetic imaging with scanning nitrogen-vacancy magnetometry. This enables a sensitivity down to 3 mu T Hz-1/2 used to localize ultra-scaled magnetic defects with lateral dimensions below 50 nm. The imaging reveals the presence of magnetic inhomogeneities in correspondence of periodical geometrical modulations/anti-notches in axial magnetized nanowires that are largely undetectable with standard metrology. The features induce local fluctuations of the NWs' magnetization orientation that are sensed by SNVM and compared with magnetic force microscopy. Finally, the strong magnetic field confinement in the nanowires is leveraged to study the interaction between the stray magnetic field and the fluorescence generated by two nitrogen-vacancies contained in the probe sensor, thus clarifying the contrast formation mechanisms. We report on magnetic imaging capability with non-perturbative field distribution mapping and minimally invasive magnetic sensing using scanning nitrogen-vacancy magnetometry in axial magnetized nanowires.

The use of a variationnal perturbation method combined with finite element analysis is presented here to simulate the influence of mass-loading effects on the resonance frequency of bulk acoustic wave resonator. Computations are conducted on 2D and 3D and any shape of resonator can be considered. Predictions are compared to experimental data.

This paper presents the results of the vibration modes measurements by X-ray topography in SC-cut quartz and Y-cut unpolished langasite resonators. A comparison of these results with X-ray diffraction topography images on AT-cut quartz resonators and Y-cut polished langasite resonators pointed out the behavior of mass-loading effect with plate orientation angle and with the surface state of the piezoelectric substrate. The results of the X-ray topography investigations are compared with electrical measurements performed on the same resonators. 5MHz Sawyer, plan parallel SC-cut quartz and Y-cut unpolished langasite resonators, with 14mm plate diameter and various electrode thickness and diameters have been investigated by Xray topography on fundamental, third and fifth overtones. The measurements were performed by conventional transmission Laue setting using white beam synchrotron radiation at LURE/DCI, Orsay, France. The study by X-ray topography on SC-cut quartz resonators and unpolished Y-cut langasite resonators pointed out a good agreement with the results obtained on the same resonators by electrical measurements. The conclusion is that the SC-cut quartz resonator characteristics present a similarly harmonic dependence with those of the Y-cut langasite resonators thus revealing the stress-compensated feature of the Y-cut in langasite crystal.

This paper presents the results of the X-ray topography investigations of mass-loading influence on electrical parameters of AT-cut quartz resonators and Y-cut langasite resonators. This study reveals that the mass-loading effect on electrical parameters of Y-cut langasite resonators is smaller than in the case of AT-cut quartz resonators. The results of the X-ray topography investigations are in good agreement with electrical measurements.

In this paper the results of electrical measurements of the mass-loading influence on Y-cut langasite resonator parameters are compared with those obtained by X-ray topography analysis of the same resonators. Based on the Ballato's transmission-line analogs of the trapped-energy ;resonators vibrating in thickness-shear mode [1], the mass-loading effect on resonator characteristics was studied. The effective mass-loading, motional inductance and quality factor of langasite resonators were computed. Sawyer plan-parallel polished Y-cut langasite resonators with 14mm diameter, 5 MHz resonant frequency, Au electrodes of 7 mm diameters and various thickness were used in experiments. X-ray topography measurements were performed by conventional transmission Laue setting using the white beam synchrotron radiation on fundamental, third and fifth overtones. The results are in agreement with those obtained by electrical measurements. The comparison of X-ray diffraction topography images previously performed on AT-cut quartz resonators with X-ray topographs on langasite resonators pointed out that the Y-cut langasite resonators are less influenced by the mass-loading than the AT-cut quartz resonators.