arXiv subjects

A. A. Minnekhanov

Publications and source records attributed to A. A. Minnekhanov.

4 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↗

arXiv2020

Multifilamentary character of anticorrelated capacitive and resistive switching in memristive structures based on (CoFeB)x(LiNbO3)100-x nanocomposite

Resistive and capacitive switching in capacitor metal/nanocomposite/metal (M/NC/M) structures based on (CoFeB)x(LiNbO3)100-x NC fabricated by ion-beam sputtering with metal content x $\approx$ 8-20 at. % is studied. The peculiarity of the structure synthesis was the use of increased oxygen content ($\approx$ 2*10^-5 Torr) at the initial stage of the NC growth. The NC films, along with metal nanogranules of 3-6 nm in size, contained a large number of dispersed Co (Fe) atoms (up to ~10^22 cm^-3). Measurements were performed both in DC and AC (frequency range 5-13 MHz) regimes. When switching structures from high-resistance (Roff) to low-resistance (Ron) state, the effect of a strong increase in their capacity was found, which reaches 8 times at x $\approx$ 15 at. % and the resistance ratio Roff/Ron $\approx$ 40. The effect is explained by the synergetic combination of the multifilamentary character of resistive switching (RS) and structural features of the samples associated, in particular, with the formation of high-resistance and strongly polarizable LiNbO3 layer near the bottom electrode of the structures. The proposed model is confirmed by investigations of RS of two-layer nanoscale M/NC/LiNbO3/M structures as well as by studies of the magnetization of M/NC/M structures in the pristine state and after RS.

cond-mat.mes-hall↗

arXiv2017

Influence of Defects on Photoconductivity and Photocatalytic Activity of Nitrogen-Doped Titania

Samples of nitrogen-doped titanium dioxide (anatase, $0.2 \leq N \leq 1.0~wt\%$) prepared by the sol-gel method were investigated using X-band EPR spectroscopy, photoconductivity and photocatalysis measurements. $N\bullet$ and $NO\bullet$ paramagnetic defects in N-TiO2 have been observed; their concentrations and spin-Hamiltonian parameters were calculated. An increase both in the rate of the generation of free charge carriers and in the rate of photocatalysis was found in N-TiO2 in contrast with non-doped titania under visible light. The correlation of the density of the observed radicals with the photoconductivity and photocatalysis data is discussed.

cond-mat.mtrl-sci↗