arXiv subjects

D. I. Yakubovsky

Publications and source records attributed to D. I. Yakubovsky.

3 recordsLinked to original sources

arXiv2025

Ionic Disorder-Mediated Exfoliation and Optical Birefringence in a Non-van der Waals Oxide

The landscape of two-dimensional photonics has been dominated by van der Waals (vdW) materials. Expanding this library to include non-vdW layered systems promises enhanced environmental robustness and access to novel functionalities, such as strong ionic conductivity, yet their exfoliation remains challenging. Here, we establish Na2Zn2TeO6 (NZTO), a P2-type superionic conductor, as an exfoliable non-vdW optical material. We demonstrate that the highly disordered, mobile Na+ interlayer inherently facilitates mechanical cleavage down to few-nanometer thicknesses (about 4 nm). Optical interrogation via spectroscopic ellipsometry reveals NZTO as a wide-bandgap dielectric with pronounced optical birefringence (Delta_n about 0.25) across the visible and near-infrared spectrum. The lattice dynamics, probed by temperature-resolved Raman spectroscopy, underscore the rigidity of the [Zn2TeO6]2- framework, which remains largely decoupled from the high ionic mobility. These results identify NZTO as a compelling platform for robust, anisotropic dielectric photonics, simultaneously opening a pathway toward the convergence of ionic transport and optical control - an emerging paradigm we term iono-photonics.

physics.optics↗

arXiv2025

Record Index-Bandgap Trade-off: CdPS3 as a High-Index van der Waals Platform for Ultraviolet-Visible Nanophotonics

The development of nanophotonics is hindered by a fundamental trade-off between a material's refractive index (n) and its electronic bandgap (Eg), which severely restricts the choice of materials for short-wavelength applications. This challenge is particularly acute in the visible and ultraviolet (UV) spectra, where high-performance devices require materials that are simultaneously highly refractive and transparent. Here, we report on the van der Waals (vdW) crystal cadmium phosphorus trisulfide (CdPS3) as a solution to this long-standing problem. Through comprehensive optical and structural characterization, we show that CdPS3 possesses an anomalously high in-plane refractive index across the visible spectrum approaching 3 in the near-UV, combined with a wide indirect bandgap. This combination of properties, which circumvents the empirical Moss's law, is validated by first-principles calculations and direct near-field imaging of highly confined waveguide modes. These findings establish CdPS3 as a leading material for UV-visible photonics, opening a new pathway for the development of high-density integrated circuits and metasurfaces.

physics.optics↗

arXiv2021

Giant optical anisotropy in transition metal dichalcogenides for next-generation photonics

Large optical anisotropy observed in a broad spectral range is of paramount importance for efficient light manipulation in countless devices. Although a giant anisotropy was recently observed in the mid-infrared wavelength range, for visible and near-infrared spectral intervals, the problem remains acute with the highest reported birefringence values of 0.8 in BaTiS3 and h-BN crystals. This inspired an intensive search for giant optical anisotropy among natural and artificial materials. Here, we demonstrate that layered transition metal dichalcogenides (TMDCs) provide an answer to this quest owing to their fundamental differences between intralayer strong covalent bonding and weak interlayer van der Walls interaction. To do this, we carried out a correlative far- and near-field characterization validated by first-principle calculations that reveals an unprecedented birefringence of 1.5 in the infrared and 3 in the visible light for MoS2. Our findings demonstrate that this outstanding anisotropy allows for tackling the diffraction limit enabling an avenue for on-chip next-generation photonics.

physics.app-ph↗