Search

Designing materials with advanced functionalities is the main focus of contemporary solid-state physics and chemistry. Research efforts worldwide are funneled into a few high-end goals, one of the oldest, and most fascinating of which is the search for an ambient temperature superconductor (A-SC). The reason is clear: superconductivity at ambient conditions implies being able to handle, measure and access a single, coherent, macroscopic quantum mechanical state without the limitations associated with cryogenics and pressurization. This would not only open exciting avenues for fundamental research, but also pave the road for a wide range of technological applications, affecting strategic areas such as energy conservation and climate change. In this roadmap we have collected contributions from many of the main actors working on superconductivity, and asked them to share their personal viewpoint on the field. The hope is that this article will serve not only as an instantaneous picture of the status of research, but also as a true roadmap defining the main long-term theoretical and experimental challenges that lie ahead. Interestingly, although the current research in superconductor design is dominated by conventional (phonon-mediated) superconductors, there seems to be a widespread consensus that achieving A-SC may require different pairing mechanisms. In memoriam, to Neil Ashcroft, who inspired us all. © 2022 The Author(s). Published by IOP Publishing Ltd. Yundi Quan has provided many useful discussions on this topic, and assistance with preparation of the figures in this paper. Giustino’s review [12] contains a wealth of references on this topic. This work was supported by US National Science Foundation Grant DMR 1607139. 3. We acknowledge Ashkan Salamat, Elliot Snider, Nathan Dasenbrock-Gammon, Raymond McBride, Mathew Debessai for useful discussions. This was supported by NSF, Grant No. DMR-1809649, and by the DOE Stockpile Stewardship Academic Alliance Program, Grant No. DE-NA0003898.5. CH acknowledges support from the Austrian Science Fund (FWF) Project No. P 32144-N36. 6. This work was supported principally by the US National Science Foundation (DMR-1933622), and by the US Department of Energy (DE-SC0020340 and DE-NA0003975). 7. I would like to thank all my collaborators and friends that contributed to this work: D M Ceperley, M Holzmann, V Gorelov, G Rillo, Y Yubo, M A Morales. This work was supported by ANR-France under the program ‘Accueil de Chercheurs de Haut Niveau 2015’ project: HyLightExtreme. 8. MA acknowledges support from the Swiss National Science Foundation (Project P4P4P2-180669). 9. This work was supported by the National Natural Science Foundation of China (Grant Nos. 52090024 and 12074138), the Science Challenge Project (Grant No. TZ2016001), the Fundamental Research Funds for the Central Universities (Jilin University, JLU), the Program for JLU Science and Technology Innovative Research Team (JLUSTIRT), and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB33000000) 10. ANK acknowledges the support through the NSF Award No. DMR-1821815. 11. We thank the Russian Science Foundation (Grant 19-72-30043) for support. 12. I thank Alice Shipley and Michael Hutcheon for their careful reading of the manuscript and insightful comments. This work has been funded by the EPSRC over many years (Projects EP/G007489/1 and EP/P022596/1), and through a Royal Society Wolfson Research Merit Award. 13. We acknowledge the National Science Foundation (DMR-1827815) for financial support. 14. The author acknowledges the financial support by JSPS KAK-ENHI Grant No. 19H05825. 15. This research was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Program (Grant Agreement No. 802533). 16. We acknowledge financial support by the European Research Council Advanced Grant FACT (ERC-2017-AdG-788890). AS acknowledges hospitality of the Physics Department of La Sapienza, under the program ‘Professori Visitatori 2020’. 17. ERM acknowledges support from the National Science Foundation (Award No. OAC-1740263). 18. The work was supported by the US Department of Energy Basic Energy Sciences under Contract No. DE-SC-0020385. 19. We thank G Profeta and G Lamura for fruitful scientific discussions. We acknowledge funding from the MIUR PRIN-2017 program (Grant No. 2017Z8TS5B—‘Tuning and understanding Quantum phases in 2D materials—Quantum2D’). 20. We thank G Profeta and G Lamura for fruitful scientific discussions. We acknowledge funding from the MIUR PRIN-2017program (Grant No. 2017Z8TS5B—‘Tuning and understanding Quantum phases in 2D materials—Quantum2D’). 21. We acknowledge financial support by the Deutsche Forschungs-Gemeinschaft through Grant (DFG) for funding through TRR 288–422213477 (B05). This research was supported in part by the National Science Foundation under Grant No. NSF PHY-1748958.

We have optimised a hybrid mode-locked holmium-doped fibre laser and a holmium-doped fibre amplifier for obtaining stable pulses as short as possible. Temporal and spectral characteristics of pulsed light have been measured as functions of pump power. Lasing has been achieved in the wavelength range 2066 – 2068 nm, with a full width at half maximum of the emission spectrum from 3 to 4 nm. The pulse duration does not exceed 1 ps and the pulse energy ranges from 0.2 to 0.5 nJ. To raise the pulse energy, holmium-doped fibre amplifiers based on two types of active fibre have been used. We have demonstrated a decrease in the width of the central part of the pulse autocorrelation function and considerable broadening of the spectrum of the pulses. The maximum average power at the amplifier output exceeds 200 mW.

We report a new solid-state waveguide laser generating picosecond pulses with a GHz repetition rate, based on the use of graphene as a saturable absorber. Lasing at the main transverse mode is provided by the geometry of a cylindrical waveguide formed in the active crystal volume by the method of direct writing with a femtosecond laser beam. Fine tuning of the intracavity interferometer formed between the active medium and output mirror makes it possible to control the spectral-temporal parameters of output radiation and to smoothly tune the repetition rate of pulses having a duration of less than 20 ps. In particular, the possibility of dual-wavelength generation in the regime of continuous passive mode locking using a single saturable absorber based on graphene is demonstrated. By amplifying laser output radiation in the ytterbium fibre amplifier, an average output power of 530 mW is obtained.

Here we report on the studies of the controllable synthesis of large area boron nitride films by the resistive heating method on a metal substrate without using a dangerous boron and nitrogen containing gases. In our original home-made CVD setup, we used the copper foil as a metal catalytic substrate. With the solid precursor of ammonia borane, the boron nitride films were synthesized under low pressure conditions and at a growth temperature of about 1000°C. We obtained the films with an area of up to 1x1 cm2 by varying the synthesis parameters. The quality of boron nitride films was characterized using Raman spectroscopy and X-ray spectroscopy.

We study the conditions of suppressed backward scattering in optical oligomers. Optical oligomers are closely packed clusters of nanoparticles which support multiple resonances, allowing to achieve scattering phase rotation by 2π necessary for metalenses. In this paper we consider the simplest oligomer — a dimer, which is irradiated by a normally-incident plane wave with the magnetic field oriented along the dimer axis. Using the dipole approximation, we have derived analytically the generalized Kerker condition for this system. Similarly to a single sphere case, the electric and magnetic dipole have to be of the same amplitude to suppress the backward scattering. However, due to the inter-particle coupling, the full coupled-dipole problem must be solved to find the wavelength of the backscattering suppression. Using the coupled-dipole and coupled-multipole methods, we have found that the Kerker condition wavelength for the considered dimer is red-shifted compared to a single sphere.

We present a simple and affordable method for making a surface electrodynamic trap for microparticles. The principles of electrodynamic trapping of charged particles are discussed and step-by-step instructions on how to make a surface trap are given. In addition to the electrodynamic trap implementation and operation process, options for its further use are proposed. The work may be of interest to physics teachers as a material for practical work, for the formation of students’ skills in performing a physical experiment.

The growing requirements for mobile communication networks (data transfer rates over 100 Gbps) makes it necessary to use carrier signal with a frequency of at least 100 GHz. This requires the development of cheap and broadband sub-terahertz (sub-THz) detectors. Here we report on our recent efforts toward the development of a heterodyne sub-THz detector based on a single layer graphene two-terminal device integrated with a bowtie antenna on a sapphire substrate. Our detector operates at frequency of 140 GHz, which corresponds to the maximum transmission of THz radiation in the Earth’s atmosphere. The heterodyne detection is achieved by quasi-optical coupling of signals from two sub-THz radiation sources to the same detector. The measured frequency bandwidth is 5.8 GHz.

The article presents the results of an experimental study of ultrasonic action on monocrystalline silicon samples. The influence of the processing modes on the surface strength of the material under study was found.

We report on the fabrication of a terahertz detector utilizing a SiO2/graphene/SiO2 sandwich suspended at the planar antenna feed. This design of the detector aims to enhance its sensitivity via weakening of the heat sink between graphene’s phonons and those of the substrate. We achieve complete suspension of the sandwich only in case of a low fill-factor of the antenna feed area. Evaluated DC parameters of the samples are consistent with those reported in the literature. The fabrication process developed is suitable for implementing the detector proposed for signal frequencies up to several terahertz.

The paper presents an analysis of field and experimental studies of the main physicochemical parameters of oil-contaminated soils of floodplain ecosystems of the middle taiga subzone of Western Siberia. The features and main regularities of their change in different pollution zones (epicenter - impact zone) are revealed. The state of the physicochemical parameters of technogenically contaminated soils is compared with background analogs. The most important groups of chemical compounds and elements that pose an environmental hazard are considered - oil and oil products, technogenic readily soluble salts (including their toxic compounds), the ways of their migration, transformation and accumulation in contaminated soils. General recommendations are given on the use of the discovered regularities in the technical maps of reclamation measures and the system for monitoring contaminated soils.

A single-wavelength compact diode-pumped solid-state laser based on a single-mode waveguide with a diameter of 20 µm and graphene saturable absorber is presented in this work. The total reflection coefficient of the intracavity interferometer has a significant effect on the level of intracavity losses. By accurate controlling the intracavity losses a stable continuous wave passive mode-locking at wavelength of 1064 nm with a pulse repetition rate of 9.5 GHz was obtained.

We consider quality (Q) factor of accidental bound states in the continuum in bilayer resonators consisting of low-index dielectric rods. The dependence of Q factor on the number of periods shows that Q factors increase with the increasing number of rods. We calculated the dependence of the resonator Q factor on the disorder by two methods: analytical (multiple scattering theory) and numerical (finite difference method) and showed that the results are in good agreement. Also, we investigated the dependence of the resonance frequency on disorder.

We propose a new concept of an active narrowband filter based on a 2.5D metasurface from Ge2Sb2Te5 (GST). In this paper, we present a numerical calculation of the transmission spectrum from a structure of ellipsoids of revolution. For this 2.5D metasurface, modulation of narrow peaks in the IR range for s- and p-polarization is shown. A manufacturing technique using two-photon lithography and laser electrodispersion is proposed.

The results of spectral noise power density measurements of reed switches 10 samples with and without Au-Ru coating are analyzed. The dependences of the spots area formed during switching tests on the electrodes on various noise parameters are constructed.

In the present paper perovskite radiation enhancement on crystalline GST film compared to amorphous one has been studied. The photonic local density of states has been calculated by angular spectrum representation of the dyadic Green’s function. The Purcell factor has been calculated for perovskite luminescent on both amorphous and crystalline GST film. Almost 80% enhancement has been observed at wavelength 950 nm for system with perovskite thickness 25 nm, GST thickness 110 nm.

We study a silicon-based structure composed of parallel rods arranged in a periodic array. The structure supports guided modes which due to the deformation of structure in general become leaky modes. At the same time the modes split at the Brillouin zone surface by a pair with certain symmetry. Here we report on guided modes transformation into symmetry-protected BIC under deforming the structure, because of inherent field distribution governed by the Bragg-related mode hybridization.