Cr_(1+δ)Te₂ are pseudo-layered compounds consisting of CrTe₂ transition metal dichalcogenide (TMD) layers with additional (δ) self-intercalated Cr atoms. The recent search for ferromagnetic 2D materials revived the interest into chromium tellurides. Here, Cr_(1+δ)Te₂ nanolayers are epitaxially grown on MoS₂ (0001), forming prototypical van der Waals heterostructures. Under optimized growth conditions, ultrathin films of only two TMD layers with a single intercalated Cr-layer are achieved, forming a 2D sheet with van der Waals surfaces. Detailed compositional and structural characterization by scanning tunneling microscopy, grazing incidence x-ray diffraction, and high-resolution Rutherford backscattering indicate the layer-by-layer growth and that the δ can be tuned by post-growth annealing in a range between ∼0.5 and 1. X-ray magnetic circular dichroism and magnetometry measurements demonstrate that all self-intercalated Cr_(1+δ)Te₂ nanolayers exhibit strong ferromagnetism with magnetic moments larger than 3μ_B per Cr-atom. The magnetic properties are maintained in the ultrathin limit of a material with a single intercalation layer. Interestingly, the magnetic anisotropy can be tuned from close to isotropic (δ = 1) to a desirable perpendicular anisotropy for low δ values. Thus, the bottom-up growth of these 2D Cr_(1+δ)Te₂ sheets is a promising approach for designing magnetic van der Waals heterostructures.

Titanium nitride is a well-known conductive ceramic material that has recently experienced resumed attention because of its plasmonic properties comparable to metallic gold and silver. Thus, TiN is an attractive alternative for modern and future photonic applications that require compatibility with the Complementary Metal-Oxide-Semiconductor (CMOS) technology or improved resistance to temperatures or radiation. This work demonstrates that polycrystalline TiN_x films sputtered on silicon at room temperature can exhibit plasmonic properties continuously from 400 nm up to 30 μm. The films’ composition, expressed as nitrogen to titanium ratio x and determined in the Secondary Ion Mass Spectroscopy (SIMS) experiment to be in the range of 0.84 to 1.21, is essential for optimizing the plasmonic properties. In the visible range, the dielectric function renders the interband optical transitions. For wavelengths longer than 800 nm, the optical properties of TiN_x are well described by the Drude model modified by an additional Lorentz term, which has to be included for part of the samples. The ab initio calculations support the experimental results both in the visible and infra-red ranges; particularly, the existence of a very low energy optical transition is predicted. Some other minor features in the dielectric function observed for the longest wavelengths are suspected to be of phonon origin.

Topological nodal-line semimetals represent a unique class of materials with intriguing electronic structures and rich of symmetries, hosting electronic states with nontrivial topological properties. Among these, $\mathrm{ZrA}{\mathrm{s}}_2$ stands out, characterized by its nodal lines in a momentum space, governed by nonsymmorphic symmetries. This study integrates angle-resolved photoemission spectroscopy (ARPES) with density functional theory (DFT) calculations to explore the electronic states of $\mathrm{ZrA}{\mathrm{s}}_2$. Our study provides experimental evidence of nonsymmorphic symmetry-protected band crossing and nodal lines in $\mathrm{ZrA}{\mathrm{s}}_2$. In ARPES scans, we observed a distinctive surface and bulk states at different photon energies associated with nodal lines. Our results, supported by calculations based on DFT, unveil such impervious band crossing anchored at specific points in the Brillouin zone, with particular emphasis on the $S$ point. Surface bands and bulk states near the crossing are elucidated through slab calculations, corroborating experimental findings. These findings enhance our understanding of the electronic structure of $\mathrm{ZrA}{\mathrm{s}}_2$.

We present a Raman study of $\mathrm{ZrA}{\mathrm{s}}_2$ single crystals, a nodal-line semimetal with symmetry-enforced Dirac-like band crossings. We identified the symmetry of phonon modes by polarized light measurements and comparison with calculated phonon frequencies. Significant dependence of peak intensities on the excitation wavelength was observed, indicating quantum interference effects. Phonon peaks in the spectra were superimposed on the electronic background, with quasielastic scattering observed for the 785-nm excitation. The temperature dependence of phonon peaks’ linewidth indicates that the electron-phonon coupling plays an essential role in phonon decay.