Anita Guarino

Correlated materials with competing spin–orbit and crystal‐field interactions can host composite spin–orbital magnons that are highly susceptible to structural and electronic perturbations, enabling the control of magnetic dynamics beyond spin‐only physics. Using Raman spectroscopy on , we show that the partial substitution of Ru with Mn reconstructs the magnon spectrum and reveals one–magnon modes that are hidden in the undoped state. We demonstrate that the transition‐metal substitution activates otherwise symmetry‐forbidden magnon modes through mirror‐symmetry breaking of the underlying spin–orbital configuration. This effect can be theoretically explained by the local structural distortions induced in the octahedra near the dopant, which enable the observation of mixed‐parity one–magnon modes. These excitations display a distinctive polarization dependence, with a lowering from fourfold to twofold rotational symmetry arising from the mixed‐parity character of the coupled magnons and interference between resonant and nonresonant scattering channels. Our results show that spin–orbit–lattice entanglement provides a route to tailoring collective magnetic excitations and their polarization response in spin–orbit–coupled correlated systems.

Lowering the operating temperature of Solid Oxide Fuel Cells (SOFCs) is essential for improving durability and enabling large‑scale commercialization. Mixed ionic–electronic conductors (MIECs) of the Ruddlesden–Popper family, such as Nd₂Ni₁₋ₓCuₓO₄₊δ (NNCO), offer attractive cathode properties due to their high oxygen transport and favourable defect chemistry. In this work, we investigate the fabrication of Nd₂Ni₀.₈Cu₀.₂O₄₊δ thin films using a room‑temperature RF sputtering process followed by moderate‑temperature annealing. To simplify deposition, a single stoichiometric target was employed, despite the compositional challenges posed by elements with different sputtering yields. We examine the effect of sputtering power density on phase formation and film stoichiometry through X‑ray diffraction, Rutherford Backscattering Spectrometry, Energy‑Dispersive X‑ray Spectroscopy, and temperature‑dependent resistivity measurements.Increasing the sputtering power density strongly reduces the presence of spurious phases and promotes stabilization of the desired n=1 Ruddlesden–Popper phase. Films deposited at 230 W (3.1 W·cm⁻²) exhibit a predominant NNCO structure, elemental ratios close to nominal composition, and resistivity values consistent with bulk materials. These findings demonstrate that high‑power sputtering combined with ex‑situ annealing enables the production of NNCO thin films suitable for SOFC cathodes. The results support the potential of PVD‑based approaches for scalable fabrication of advanced SOFC components.

Bi₂Se₃ thin films with different thicknesses are deposited on prepatterned n-Si substrates by the vapor–solid deposition method, demonstrating photodetector performances in the visible and near-infrared range up to the telecommunication wavelength 1550 nm and showing response times as low as 126 ns. The current voltage characteristics measured in the temperature range 77–300 K indicate the formation of Schottky junctions at the interface between the two materials. The nature of the junctions is discussed considering the effect of disorder at the interface induced by the Bi₂Se₃ film granularity. The temperature dependence of the ideality factors and the Schottky barrier heights is consistent with a thermionic field effect mechanism governing the electron motion through the interface, which is responsible for the fast response of the photodetectors.

The relation between crystal symmetries, electron correlations and electronic structure steers the formation of a large array of unconventional phases of matter, including magneto-electric loop currents and chiral magnetism^1–6. The detection of such hidden orders is an important goal in condensed-matter physics. However, until now, non-standard forms of magnetism with chiral electronic ordering have been difficult to detect experimentally⁷. Here we develop a theory for symmetry-broken chiral ground states and propose a methodology based on circularly polarized, spin-selective, angular-resolved photoelectron spectroscopy to study them. We use the archetypal quantum material Sr₂RuO₄ and reveal spectroscopic signatures that, despite being subtle, can be reconciled with the formation of spin–orbital chiral currents at the surface of the material^8–10. As we shed light on these chiral regimes, our findings pave the way for a deeper understanding of ordering phenomena and unconventional magnetism.

Point-contact spectroscopy was performed on bulk samples of electron-doped high temperature superconductor Nd_2−xCe_xCuO_4−δ. The samples were characterized using X-ray diffraction and scanning electron microscopy equipped with a wavelength-dispersive spectrometer and an electron backscatter diffraction detector. Samples with Ce content x = 0.15 showed the absence of spurious phases and randomly oriented grains, most of which had dimensions of approximately 220 µm². The low-bias spectra in the tunneling regime, i.e., high-transparency interface, exhibited a gap feature at about ±5 meV and no zero-bias conductance, despite the random oriented grains investigated within our bulk samples, consistent with most of the literature data on oriented samples. High-bias conductance was also measured in order to obtain information on the properties of the barrier. A V-shape was observed in some cases, instead of the parabolic behavior expected for tunnel junctions.

Point-contact spectroscopy has been performed on bulk samples of electron-doped high temperature superconductor Nd2-xCexCuO4-. The samples were characterized by X-ray diffraction and scanning electron microscopy equipped with a wavelength dispersive spectrometer and an electron backscatter diffraction detector. The samples with a Ce content x = 0.15, show the absence of spurious phases and randomly oriented grains, most of which have dimensions of approximately 220 µm2. The low-bias spectra in the tunnelling regime, i.e., high transparency interface, exhibit a gap feature at about ±5 meV and no zero-bias conductance, consistent with the most literature data on oriented samples. The high-bias conductance has also been measured in order to obtain information on the properties of the barrier. A V-shape has been in some cases observed, instead of the parabolic behavior expected for tunnel junctions.