Ionic Disorder-Mediated Exfoliation and Optical Birefringence in a Non-van der Waals Oxide
Abstract
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.
Keywords
Cite
@article{arxiv.2512.09248,
title = {Ionic Disorder-Mediated Exfoliation and Optical Birefringence in a Non-van der Waals Oxide},
author = {N. V. Pak and M. K. Tatmyshevskiy and I. A. Kruglov and K. V. Kravtsov and A. A. Minnekhanov and D. V. Grudinin and A. N. Toksumakov and A. S. Slavich and D. I. Yakubovsky and A. A. Vyshnevyy and M. A. El-Sayed and G. A. Ermolaev and A. V. Arsenin and V. S. Volkov},
journal= {arXiv preprint arXiv:2512.09248},
year = {2025}
}