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The transition from planar (2D) 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 parts. The first section 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 Lorentz electron Ptychography provide sub-nanometer 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 section 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 section 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.

When performing optical high-speed single-molecule spectroscopy and identification, low signal intensities pose a challenge. Fortunately, for many applications, the number of possible molecules in the specimen is small or limited. For such cases, a protocol is presented that uses only a small number of very sensitive hence expensive detectors. The protocol starts with optimizing spectral regions, one per detector, so that different molecules become best distinguishable. Experimentally, the spectral regions are extracted from the continuous spectrum using a custom-made micro-optical element. In the ray-optics picture, it guides all rays in a spectral region onto the entrance of an optical fiber connected to one detector. The shape of the micro-optical element is derived by applying Snell's law to the given geometrical boundary conditions. A proof-of-concept measurement using a dedicated demonstrator refractive optical element in combination with a continuous white-light source is performed. Indeed, the element selects the correct spectral regions and couples the light into the correct fibers. For the example of the identification of single amino acids in a protein, the protocol leads to a higher correct identification rate. Therefore, this protocol is useful for such protein identification experiments as performed in the EU project ProID.

Dry synthesis is a highly versatile method for the fabrication of nanoporous metal films, since it enables easy and reproducible deposition of single or multi-layers of nanostructured materials that can find intriguing applications in plasmonics, photochemistry and photocatalysis, to name a few. Here, we extend the use of this methodology to the preparation of copper nano-islands that represent an affordable and versatile example of disordered plasmonic substrates. Although the island morphology is disordered, the high density of these nanostructures with large surface area results in a good homogeneity on a macroscale, which is beneficial for plasmonic applications such as bio-sensing and photo-catalysis. With cathodoluminescence and electron-energy-loss spectroscopies we confirm the nano-islands as sources of the local field enhancement and identify the plasmonic resonance bands in the visible and near-infrared spectral range. The decay dynamics of the plasmonic signal are slower in the nano-island as compared to bulk copper films, which can be rationalized by a reduced energy dissipation in the nano-island films. Our study demonstrates a robust and lithography-free fabrication pathway to obtain nanostructured plasmonic copper substrates that represent a highly versatile low-cost alternative for future applications ranging from sensing to photochemistry and photocatalysis.

Doped semiconductors can exhibit metallic-like properties ranging from superconductivity to tunable localized surface plasmon resonances. Diamond is a wide-bandgap semiconductor that is rendered electronically active by incorporating a hole dopant, boron. While the effects of boron doping on the electronic band structure of diamond are well-studied, any link between charge carriers and plasmons has never been shown. Here, we report intervalence plasmons in boron-doped diamond, defined as collective electronic excitations between the valence subbands, opened up by the presence of holes. Evidence for these low-energy excitations is provided by valence electron energy loss spectroscopy and near-field infrared spectroscopy. The measured spectra are subsequently reproduced by first-principles calculations based on the contribution of intervalence band transitions to the dielectric function. Our calculations also reveal that the real part of the dielectric function exhibits a crossover characteristic of metallicity. These results suggest a new mechanism for inducing plasmon-like behavior in doped semiconductors, and the possibility of attaining such properties in diamond, a key emerging material for quantum information technologies.

Layered two-dimensional (2D) materials have revolutionized how we approach light–matter interactions, offering unprecedented optical and electronic properties with the potential for vertical heterostructures and manipulation of spin–valley degrees of freedom. The discovery of moiré physics in twisted heterostructures has further unlocked new possibilities for controlling the band structure of tailored semiconductor heterostructures. In parallel, the integration of 2D materials with hybrid photonic structures and ultrafast studies on their optical and spin–valley properties has revealed a wealth of novel physical phenomena. This perspective highlights the recent advances in our understanding of light–matter interactions in moiré and 2D systems, with a particular emphasis on ultrafast processes and the integration of these materials into photonic platforms. We explore the implications for optoelectronics and emerging photonic technologies, positioning 2D materials as a transformative tool for next-generation devices.

Nanoporous metals are a class of nanostructured materials finding extensive applications in multiple fields thanks to their unique properties attributed to their high surface area and interconnected nanoscale ligaments. They can be prepared following different strategies, but the deposition of an arbitrary pure porous metal is still challenging. Recently, a dry synthesis of nanoporous films based on the plasma treatment of metal thin layers deposited by physical vapour deposition has been demonstrated, as a general route to form pure nanoporous films from a large set of metals. An interesting aspect related to this approach is the possibility to apply the same methodology to deposit the porous films as a multilayer. In this way, it is possible to explore the properties of different porous metals in close contact. As demonstrated in this paper, interesting plasmonic properties emerge in a nanoporous Au–Ag bi-layer. The versatility of the method coupled with the possibility to include many different metals, provides an opportunity to tailor their optical resonances and to exploit the chemical and mechanical properties of components, which is of great interest to applications ranging from sensing, to photochemistry and photocatalysis.

We use a vortex retarder approach to generate few optical cycles light pulses carrying orbital angular momentum and arbitrary polarization. The optical vortices' structure is then reconstructed in the spatio-temporal domain.

Plasmonic metasurfaces with spatial symmetry breaking are crucial materials with significant applications in fields such as polarization-controlled photonic devices and nanophotonic platforms for chiral sensing. In this paper, we introduce planar plasmonic metasurfaces, less than one-tenth of a wavelength thick, featuring nanocavities formed by three equilateral triangles. This configuration creates uniform, thin metasurfaces. Through a combination of experimental measurements and numerical modeling, we demonstrate the inherent superchirality of these plasmonic metasurfaces. We address the challenge of achieving a strong enhancement of optical chirality in the visible spectrum, reaching levels comparable to those of 3D chiral metasurfaces.

Nickel (II) oxide, NiO, is a wide band gap Mott insulator characterized by strong Coulomb repulsion between d-electrons and displays antiferromagnetic order at room temperature. NiO has gained attention in recent years as a very promising candidate for applications in a broad set of areas, including chemistry and metallurgy to spintronics and energy harvesting. Here, we report on the fabrication of polycrystalline NiO using spray-pyrolysis technique, which is a deposition technique able to produce quite uniform films of pure and crystalline materials without the need of high vacuum or inert atmospheres. The composition and structure of the NiO thin films were then studied using x-ray diffraction, and atomic force and scanning electron microscopies (SEM). The phononic and magnonic properties of the NiO thin films were also studied via Raman spectroscopy, and the ultrafast electron dynamics by using optical pump probe spectroscopy. We found that the NiO samples display the same phonon and magnon excitations expected for single crystal NiO at room temperature, and that electron dynamics in our system is like those of previously reported NiO mono- and polycrystalline systems synthesized using different techniques. These results prove that spray-pyrolysis can be used as affordable and large-scale fabrication technique to synthesize strongly correlated materials for a large set of applications.

Currently, there is a high interest in novel plasmonic platforms and materials able to extend their applicability into the ultraviolet (UV) region of the electromagnetic spectrum. In the UV it is possible to explore the spectral properties of biomolecules that have only a small cross-section in the visible spectral range. However, most plasmonic metals have their resonances at wavelengths >350 nm. Aluminum and rhodium are two exceptions and therefore interesting candidate materials for UV plasmonics. In this work we developed a simple and low-cost preparation of functional substrates based on nanoporous aluminum decorated with rhodium nanoparticles. We demonstrate that these functionalized nanoporous metal films can be exploited as plasmonic materials for enhanced UV Raman spectroscopy.