Publications

Miniaturization of optical devices is a modern trend essential for optoelectronics, optical sensing, optical computing and other branches of science and technology. To satisfy this trend, optical materials with a small footprint are required. Here we show that extremely thin, flat, nanostructured gold films made of highly-oriented single-crystalline gold quantum-dots can provide elements of topological photonics in visible light and be used as high-index dielectric materials in the infrared part of the spectra. We measure and theoretically confirm the presence of topological darkness and associated phase singularities in studied gold films of thickness of below 10 nm placed on MgO substrates in the red part of the spectrum. At telecom wavelengths, the fabricated gold metasurface behaves as a dielectric with the refractive index of n~2.75 and the absorption coefficient of k~0.005.

Design and engineering of novel low dimensional metamaterials allow for new applications in membrane technology, aerospace and automotive industries, architecture, robotics, medicine, and textiles. Such materials can be strong, flexible, transparent, and can be assigned with different functionalities. Here, the authors explore the possibility of 2D graphene oxide (GO) surface to guide self‐assembly of 4‐cyano‐4′‐pentylbiphenyl (5CB) molecules via multiple hydrogen bonding and their clustering in optically active phases. The encapsulation of 5CB in a 2D geometry and birefringent properties of 5CB are tuned by the regulation of interaction energy between GO surface and 5CB. Chemical reduction of GO‐5CB composites results in electrically conductive reduced graphene oxide‐5CB membranes which change optical properties in response to Joule heating. The sustainable approach to the design of robust and flexible optically active materials will allow the formation of other metamaterials with different functionalities for advanced applications.

No abstract is provided for this article.

Personal protective clothing is critical to shield users from highly infectious diseases including COVID-19. Such clothing is predominantly single-use, made of plastic-based synthetic fibres such as polypropylene and polyester, low cost and able to provide protection against pathogens. However, the environmental impacts of synthetic fibre-based clothing are significant and well-documented. Despite growing environmental concerns with single-use plastic-based protective clothing, the recent COVID-19 pandemic has seen a significant increase in their use, that could result in a further surge of oceanic plastic pollution, adding to mass of plastic waste that already threatens marine life. In this review, we briefly discuss the nature of the raw materials involved in the production of such clothing, as well as manufacturing techniques and the PPE supply chain. We identify the environmental impacts at critical points in the protective clothing value chain from production to consumption, focusing on water use, chemical pollution, CO2 emissions and waste. On the basis of these environmental impacts, we outline the need for fundamental changes in the business model, including increased usage of reusable protective clothing, addressing supply chain bottlenecks, establishing better waste management, and the use of sustainable materials and processes without associated environmental problems.

We report a new nonlocal effect in vortex matter, where an electric current confined to a small region of a long and sufficiently narrow superconducting wire causes vortex flow at distances hundreds of intervortex separations away. The observed remote traffic of vortices is attributed to a very efficient transfer of a local strain through the one-dimensional vortex lattice (VL), even in the presence of disorder. We also observe mesoscopic fluctuations in the nonlocal vortex flow, which arise due to "traffic jams" when vortex arrangements do not match a local geometry of a superconducting channel.

We performed a metrological characterization of the quantum Hall resistance in a 1 μm wide graphene Hall bar. The longitudinal resistivity in the center of the ν=±2 quantum Hall plateaus vanishes within the measurement noise of 20 mΩ up to 2 μA. Our results show that the quantization of these plateaus is within the experimental uncertainty (15 ppm for 1.5 μA current) equal to that in conventional semiconductors. The principal limitation of the present experiments is the relatively high contact resistances in the quantum Hall regime, leading to a significantly increased noise across the voltage contacts and a heating of the sample when a high current is applied.

The topological structure associated with the branch point singularity around an exceptional point (EP) can provide tools for controlling the propagation of light. Through use of graphene-based devices, we demonstrate the emergence of EPs in an electrically controlled interaction between light and a collection of organic molecules in the terahertz regime at room temperature. We show that the intensity and phase of terahertz pulses can be controlled by a gate voltage, which drives the device across the EP. Our electrically tunable system allows reconstruction of the Riemann surface associated with the complex energy landscape and provides topological control of light by tuning the loss imbalance and frequency detuning of interacting modes. Our approach provides a platform for developing topological optoelectronics and studying the manifestations of EP physics in light–matter interactions.

Ultrasmall-scale semiconductor devices (≤5 nm) are advancing technologies, such as artificial intelligence and the Internet of Things. However, the further scaling of these devices poses critical challenges, such as interface properties and oxide quality, particularly at the high-

No abstract is provided for this article.

No abstract is provided for this article.

No abstract is provided for this article.

Highly confined phonon polaritons enable strong light-matter interactions that tailor incandescent heat sources for enhanced thermal emission in both the near- and far-field regimes. However, single polar dielectric materials are limited in both the emission spectral range and achievable mode confinement. In this study, we employ a bilayer structure comprising monolayer hexagonal boron nitride (h-BN) integrated with silicon dioxide (SiO₂) to exploit confined phonon polariton modes across a broadened energy spectrum. The distinct, nonoverlapping Reststrahlen bands of h-BN and SiO₂ provide multiple spectral channels for polaritonic enhancement, improving far-field emission. We report a 3.4-fold enhancement in emissivity with the addition of h-BN to a SiO₂ nanoribbon. We identify the confined modes within the Reststrahlen bands with numerical modeling, revealing the enhancement mechanism. This effect is verified with direct thermal measurements by using a thermal bridge method, yielding a peak emissivity of 0.6. This work offers insights into engineering broad-band polaritonic thermal emitters.

Josephson junctions (JJs) are key to superconducting quantum technologies and the search for self-conjugate quasiparticles potentially useful for fault-tolerant quantum computing. In topological insulator (TI)–based JJs, measuring the current-phase relation (CPR) can reveal unconventional effects such as Majorana bound states (MBS) and nonreciprocal transport. However, reconstructing CPR as a function of magnetic field has not been attempted. Here, we present a platform for field-dependent CPR measurements in planar JJs made of NbSe 2 and few-layer Bi 2 Se 3 . When a flux quantum <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m1" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi mathvariant="normal">Φ</mml:mi> <mml:mn>0</mml:mn> </mml:msub> </mml:mrow> </mml:math> threads the junction, we observe anomalous peak-dip CPR structure and nonreciprocal supercurrent flow. We show that these arise from a nonuniform supercurrent distribution that also leads to a robust and tunable Josephson diode effect. Furthermore, despite numerous previous studies, we find no evidence of MBS. Our results establish magnetic field–dependent CPR as a powerful probe of TI-based superconducting devices and offer design strategies for nonreciprocal superconducting electronics.