Seznam abstraktů 2025: POSTEROVÁ SEKCE A

The development of solar-blind ultraviolet (UV) photodetectors for wavelengths below 280 nm remains a key challenge in the field of modern optoelectronics. Materials with bandgaps >4.4 eV (e.g. AlxGa1−xN, Ga2O3 and diamond) are recognized as suitable for deep UV detection, but single crystalline forms are often costly and limited in size. However, when polycrystalline, these films provide a lower cost, tuneable platform with versatile processing routes.
In this work, we present self-standing Ga2O3/diamond p-n heterojunction photodetectors fabricated from Si-doped Ga2O3 (n-type) and B-doped diamond (p-type) polycrystalline films. The optical response of prepared photodetectors was characterized under UV and VIS illumination from both the diamond and Ga2O3 sides. The measured I-V characteristics confirm p-n behaviour, and the photocurrents exceeded the dark current up to 2 orders of magnitude. The photodetectors exhibit pronounced solar-blind selectivity: the UV/visible rejection ratio, defined as the responsivity ratio (R232/R400 at 232 nm vs. 400 nm), exceeds values of 1,700 when illuminated from the diamond side and approx. 300 when illuminated from the Ga2O3 side (R250/R400 at 250 nm vs. 400 nm). These results clearly demonstrate that low-cost polycrystalline Ga2O3/diamond heterojunctions are a promising route to highly selective deep UV photodetection.
M.V. acknowledges support from the project IM-2023-87 funded by the Slovak Academy of Sciences via the programme IMPULZ 2023. F.G. and M.Ť. acknowledge the support by the Slovak Academy of Sciences (SAS-TUBITAK/JRP/2024/1107.C/COPS), bilateral project no. CAS-SAS-2024-08 (SAV 25-11) and EU recovery and resilience plan (09I05-03-V02-00030).

In this study, we present the temperature- and excitation wavelength-dependent Raman and photoluminescence (PL) properties of single-crystalline diamond (SCD) substrate (IIa (111) with low nitrogen content from EDP Japan), which was epitaxially overgrown with a thin diamond layer containing silicon-vacancy (SiV) centres. Raman and PL spectra were measured at four different excitation wavelengths: 405, 488, 532 and 633 nm. Temperature-dependent measurements (from 5 K to 500 K) were performed to investigate the effect of temperature on the PL of NV and SiV colour centres, as well as on the diamond Raman peak characteristics and stress-induced phenomena. The measurements revealed three PL peaks, corresponding to the NV0 (575 nm), NV- (638 nm) and SiV (738 nm) centres. For all PL peaks a red-shift of about 3 nm was observed with increasing temperature. However, the intensity of SiV and NV decreases significantly with increasing temperature. On the other hand, at low temperatures (5 - 75 K), the splitting of the SiV PL peak was observed for the excitation wavelengths of 405, 488, and 532 nm. This work was supported by the Slovak Research and Development Agency (project # APVV-23-0361). M.V. acknowledges support from the project IM-2023-87 funded by the Slovak Academy of Sciences via the programme IMPULZ 2023.

Optically active diamond is a key platform for bio-, opto-, and quantum technologies. Recent progress in the CVD technology enables wafer-scale growth with tunable properties, yet the quality is highly sensitive to the seeding step. Beyond nucleation density, recent work indicates that seed-crystal quality and shape can influence both film growth and color-center performance. Here, we ask whether inexpensive detonation soot (DS) can substitute for purified single-digit detonation nanodiamond (DND) as a seeding agent, and what impact - if any - this substitution has on CVD film morphology and the photoluminescence (PL) of silicon-vacancy (SiV) centers. DS was produced by detonation of a Composition B charge (40% TNT/60% RDX) in an ice shell and cleaned only with HCl to remove metallic residues. Aqueous DS was prepared by probe sonication and used either as (i) the full dispersion, or (ii) the supernatant after centrifugation (16,000 rcf, 1 h). For comparison, Si substrates were also seeded with a standard nucleation colloid of well-purified single-digit DND. All seeding layers and dispersions were analyzed by SEM; the dispersions by DLS, ζ-potential and FTIR. Diamond films were deposited in a focused microwave plasma reactor at 760 °C for 5-480 min and characterized by SEM, Raman spectroscopy, and PL with emphasis on SiV emission. For all three seeding types (DND, DS full, DS supernatant) we observe comparable nucleation densities and successful diamond growth. Within the explored parameter space, film morphology and SiV PL characteristics show no detectable degradation when DS-based seeds are used. These results demonstrate that minimally processed DS offers as a cost-effective seeding alternative for the CVD diamond growth, without compromising SiV-center optical response.

Diamond is a material of major importance for sensor technologies due to its chemical stability, hardness, wide band gap and biocompatibility. Nanocrystalline diamond (NCD) films are attractive, since they combine the intrinsic properties of diamond with a large surface area and tunable electronic behavior depending on surface termination. Unlike boron- or nitrogen-doped layers, which may introduce defects and reduce stability, undoped NCD films preserve structural quality and reproducible surface chemistry suitable for functionalization.

Undoped nanodiamond layers were synthesized by hot-filament chemical vapor deposition (HF-CVD) on quartz substrates. Quartz provides transparency, dielectric stability and compatibility with microfabrication processes, which is advantageous for sensor integration. Structural characterization with Raman spectroscopy and scanning electron microscopy confirmed nanocrystalline films with minimal sp² carbon admixture. Surface functionalization with hydrogen or oxygen was applied to tailor electronic properties. Hydrogen termination induces p-type surface conductivity through transfer doping, while oxygen termination maintains insulating behavior. These modifications are directly related to sensor performance. The obtained layers are proposed as a transducer for solid-gate field-effect transistors (SGFETs) and gas sensors. In SGFET structures, hydrogen-terminated nanodiamond enables sensitivity to ionic and biochemical changes, supporting bio- and chemo-sensitive devices. In gas sensing, oxygen-terminated surfaces provide selectivity, reproducibility and resistance to harsh conditions. The combination of nanocrystalline morphology, controlled functionalization and chemical robustness supports the use of these layers in multifunctional sensors. ACKNOWLEDGEMENTS: The work was performed in the frame of MNSW Poland Regional Excellence Initiative no. RID/SP/0048/2024/01 project.

This study investigates nanocrystalline diamond (NCD)-based MEMS structures incorporating silicon-vacancy (Si-V) centers. The combination of device design, the physical properties of diamond, and the optical characteristics of Si-V centers demonstrates strong potential for non-contact optical thermometry and strain sensing. Structures were fabricated using lithography and microwave plasma-enhanced chemical vapor deposition (CVD). Scanning electron microscopy (SEM) analysis confirmed the uniform thickness and nanocrystalline morphology of the diamond films. Raman spectroscopy revealed spatial variations in the diamond peak position across the MEMS structures, indicating non-uniform mechanical strain within the NCD layer.
Photoluminescence (PL) spectroscopy showed a dominant, sharp zero-phonon line (ZPL) at 738 nm, characteristic for negatively charged (Si-V)⁻ centers. The ZPL position and FWHM exhibited a linear dependence on temperature over the measured range, during heating and cooling process. These results confirm the sensitivity of Si-V centers to local strain and temperature variations. The work contributes to the growing understanding of Si-V centers in diamond and supports their future integration into quantum technologies, sensing platforms, and photonic devices.

Photonic crystals are periodic structures able to control the propagation of light, preventing photon transport in ay way analogous to electron behaviour in semiconductors. Among these, the cubic diamond structure is notable for exhibiting a complete photonic bandgap [1][2]. This makes cubic diamond an attractive candidate for photonic materials, motivating extensive research into its fabrication [3]. A promising approach involves DNA-mediated self-assembly of deformed tetrameric colloids. The four-patch geometry of these colloids prevents the formation of the hexagonal diamond, which lacks a bandgap, while enabling binding to four nearest neighbours, thereby producing a cubic diamond lattice [4].
Beyond perfect crystals, there is growing interest in introducing controlled disorder to achieve strong photon localization, also known as Anderson localization [5]. Sajeev John proposed realizing such states by embedding long-range order into disordered systems [6]. In contrast, this project investigates disorder introduced into an initially ordered cubic diamond crystal. The colloidal self-assembly route allows tuning of disorder by adjusting colloid deformation, patch protrusion, and rotational flexibility. Additionally, mixing slightly different particle shapes provides another mechanism to construct diamond-like structures with tailored disorder, while preserving long-range photonic properties.

The escalating global demand for energy continues to drive a significant increase in greenhouse gas emissions, a concern highlighted at the 27th Conference of the Parties, which underscored the urgent need for coordinated action toward sustainable energy systems and carbon mitigation technologies. Among the most energy-intensive industrial processes is the Haber-Bosch method for ammonia synthesis, which accounts for a substantial share of anthropogenic CO2 emissions. Given ammonia's critical role as a nitrogen source in fertilizers, identifying alternative, low-emission synthesis routes is vital for ensuring long-term food security.
In this study, we present a sustainable approach to ammonia production via electrocatalytic nitrate reduction, leveraging nitrate ions commonly present in wastewater as a nitrogen source. Our method utilizes Single Atom Catalysts (SACs), engineered by immobilizing individual copper atoms onto functionalized graphene supports. Specifically, we synthesize Cu(I)/Cu(II) mixed-valence species stabilized on nitrogen-doped graphene acid. The functional groups within the graphene lattice play a dual role: enhancing metal atom stabilization and promoting in situ reduction of Cu(II) to catalytically active Cu(I) centers. During electrocatalysis, Cu(I) sites facilitate proton adsorption and activation (forming H*ads), while Cu(II) sites coordinate with nitrate ions. The proximity of these two sites enables the transfer of H*ads to bound nitrate, promoting its stepwise reduction to ammonia. This dual-site mechanism not only offers a low-carbon route for ammonia electrosynthesis but also contributes to wastewater remediation by converting nitrate pollutants into valuable chemical products, thereby addressing both environmental and agricultural challenges.

This study examined the spinnability of expanded graphite mixed with PVB, PCL, and PLA polymers using AC electrospinning. Expanded graphite was ultrasonicated to reduce its porosity and was successfully incorporated at concentrations of up to 30% in PVA, 20% in PVB, and 10% in PCL. Although electrical resistivity decreased slightly with higher graphite loading, the improvement in conductivity was limited due to the material's high porosity. Mechanical properties measured along the fibre direction showed only minimal enhancement. The study suggests that to achieve better performance, the material should be axially compressed to increase density, which would improve conductive networks through enhanced particle-to-particle contact and increase the axial load-bearing capacity.

Cellulose-based porous carbon monoliths have attracted significant interest as sustainable materials for applications in catalysis, adsorption, and energy storage. However, preparation of these porous carbon monoliths from microcrystalline cellulose powder requires a multi-step procedure based on ice-templating effect [1] where each individual step influences total pore volume and pore size distribution of prepared monoliths.
This work investigates the impact of individual steps within this multi-step preparation procedure on the porosity characteristics—specific pore volume, specific surface area, and pore size distribution—of iron-doped, cellulose-based carbon monoliths. Microcrystalline cellulose was dissolved in precooled aqueous NaOH solution and mixed with saturated FeSO₄ solution. The resulting mixture was poured into molds and subjected to controlled freezing, (preceded by pre-heating at 85 °C for varying durations in selected samples), regeneration, washing, drying and pyrolysis.
By systematically varying each process parameter from pre-heating to pyrolysis, this study aims to elucidate their individual and combined effects on the resulting porous structure. The findings contribute to a deeper understanding of the controllable synthesis of tailored porous carbon monoliths from renewable precursors, offering pathways to optimize their textural properties for specific applications.
[1] M. P. Chavhan, A. Kryeziu, S. Ganguly, J. Parmentier: Monolithic metal-based/porous carbon nanocomposites made from dissolved cellulose for use in electrochemical capacitor. Green Carbon 2 (2024) 109-117

Antiphase boundaries (APBs) are planar crystallographic defects that play an important role in strengthening Ni-based alloys, and their sensitivity to alloy composition offers a flexible tuning parameter for alloy design. Thermal APBs in magnetic shape memory alloys affect magnetic coercivity through magnetic domain wall( DW) pinning.
Magnetic force microscopy (MFM) and Lorentz transmission electron microscopy (TEM) studies of Ni2MnGa have shown a clear difference between signals generated by a thermally induced APB and by a single magnetic DW. A change of sign of the out-of-plane component of magnetic flux (Bz) measured across the interface is a signature of APB in an in-plane magnetized sample, whereasa simple but much stronger peak of Bz indicates a single DW.
We combine experimental and theoretical (ab initio) methods to analyze the stability and magnetic ordering near the antiphase boundary in Ni2MnGa with L21 ordering. Ab initio electronic structure calculations based on density functional theory are used to investigate the magnetic ordering in a structure simulating APB’s in cubic austenite.The total energy calculations indicate that at the antiphase boundary the ferromagnetic ordering changes its orientation in the opposite direction.This sudden change in magnetization highlights the APB’s,which are then readily visible by magnetic force microscopy. We find that single APB’s,when close together, tend to attract each other and form thicker antiphase boundary complexes. The APB region with lowest ground state energy was used as an input of a magnetostatic calculationas implemented in Quantum ATK atomistic simulation software.This continuum model was used to predict magnetic contrast at length scales comparable to the MFM observation.

Histamine is a biogenic amine commonly found in fermented foods and fish products. High histamine intake can lead to histamine poisoning, resulting in an array of health consequences, and in severe cases, fatal outcomes. Hence, the detection of histamine in food is of great importance. Electrochemical sensors based on nanomaterials are a great candidate for this purpose. In this study, rGO-CuO nanocomposites were employed, and the impacts of synthesis procedures and electrochemical activation on these nanocomposites towards histamine were investigated. More specifically, rGO-CuO was synthesized by two different approaches, namely in situ and ex situ. Secondly, the physicochemical characterization of the nanomaterials was implemented by Scanning Electron Microscopy and X-ray Diffraction. Lastly, the electrochemical performance of glassy carbon electrodes modified by the nanocomposites was evaluated by Cyclic Voltammetry and Differential Pulse Voltammetry in the presence of histamine. The results indicated that the nanocomposites from the two synthesis approaches had different morphologies, resulting in two distinct electrochemical behaviours towards histamine. Furthermore, the electrochemical activation led to significant improvements for the nanocomposites from both synthesis approaches, with the electrode modified with rGO-CuO from the ex situ approach having a better peak current than the bare one and the one modified with rGO-CuO from the in situ approach.
ACKNOWLEDGEMENT: This study was supported by the project CEITEC VUT-J-25-8756, Brno University of Technology.

Inter-lanthanide perovskites exhibit interesting magnetic and optical properties. The intensity of photoluminescence (PL) emission can be influenced by the composition of the host matrix and is characterized by sharp spectral peaks from their 4f electron transitions [1, 2]. The aim of this work was to prepare selected perovskites with host matrix LaYO3 doped with ≈1 at. % Yb3+ and various concentration of Tm3+ ions (≈0; 0,02; 0,1; 0,5; 1 and 2 at. %). Perovskites were prepared by combustion synthesis and were studied their physic-chemical properties, with a focus on optical properties. In addition to the impact of the chemical composition of perovskites on the resulting properties, attention was paid to revealing the dependence of Tm3+ ion concentration on upconversion (PL) emissions.
The samples were characterized in terms of their chemical composition (EDX microanalysis), crystallites size (SEM), their crystallographic structure (XRD analysis), diffuse reflectance spectra (UV-Vis-NIR spectroscopy), and steady-state and time-resolved PL emission spectra measured at the pumping wavelength of λ ≈ 977 nm. In the perovskites, was observed the near-infrared Tm3+: 3F4 → 3H6 (λ ≈ 1.82 μm) PL Stokes and the visible Tm3+: 3H4 → 3H6 (λ ≈ 770 nm), Tm3+: 3F2, 3F3 → 3H6 (λ ≈ 670 nm) and Tm3+: 1G4 → 3H6 (λ ≈ 485 nm) PL anti-Stokes emission. Based on the PL emission spectra and the decay times of Tm3+ electronic transitions, the mechanism of upconversion PL emission was determined.

In this study, hybrid nanocomposites based on polypropylene (PP) reinforced with nano-silica (SiO2) and graphene oxide (GO) were synthesized and characterized. A melt compounding technique was used to fabricate the nanocomposites with varying contents of SiO2 (1-3 wt%) and GO (0.5-1 wt%). The thermal, mechanical, and morphological properties of the nanocomposites were evaluated using TGA, DSC, tensile testing, XRD, and SEM. Results showed significant improvements in thermal stability and tensile strength due to the synergistic effects of GO and SiO2, making the material a potential candidate for high-performance applications.

In our ongoing computational work we are in the progress of rational designing the porphyrine-based molecular device that is capable of controllable and repeatable switching between at least two states. Both states are to be stable without the impulse - external electric field, that only mediates switching between them ("writing"). Further, these states would have different characteristics, that would allow the states to be distinguished, or "reading". Porphyrines can host a variety of metals that would allow the molecule to exist in alternate spin states - singlet or triplet. We aim to utilize these different multiplicity states of metal porphyrines as states to switch between, rendering the molecule different total and spin resolved conductivity, depending on the state. Such a device would serve as a prototype for future applications in nanoelectronics as molecular memory-storage element, for example.
ACKNOWLEDGEMENTS: We acknowledge the support of Czech Science Foundation, project 25-158875 for this work.

The rapid evolution of nanoelectronics underscores the need for innovative field-effect transistor (FET) architectures that deliver enhanced performance and enable further miniaturization. This study investigates the design and fabrication potential of a multilayer nanosheet metal-dielectric-semiconductor (MDS) transistor, utilizing semiconducting graphene layers deposited on a silicon substrate and incorporating gold source and drain regions. The graphene layers form contacts with both the upper and lower surfaces of the gold electrodes, resulting in a multilayered gate and channel structure. This configuration allows the gate to fully enclose the channel, thereby improving electrostatic control and optimizing transistor performance parameters.
A comprehensive technological modeling process was conducted to define the fabrication sequence, yielding a structure composed of vertically stacked graphene channels encapsulated by silicon dioxide and polycrystalline silicon. Additionally, the study explores a cost-effective and scalable method for depositing graphene layers. This approach involves exfoliating graphite into particles containing varying numbers of graphene layers, which are then dispersed in a liquid medium. Using sharp-edged, blade-shaped probes, these particles are selectively transferred onto the substrate surface, enabling the formation of graphene layers with controlled thickness and dimensions.
The findings demonstrate that the proposed structure and fabrication method can facilitate the development of compact, high-speed MDS transistors and significantly broaden the practical applications of graphene in nano-electronic devices.

Acoustic forces enable contactless and selective manipulation of particles within microchannels, allowing precise control over their distribution and flow dynamics. This work presents the development of a glass microfluidic chip with an integrated piezoelectric element, designed for the continuous handling of functionalized polystyrene microparticles using acoustofluidic principles. The core innovation lies in the design and implementation of a system that facilitates controlled mixing of the sample with these microparticles, followed by their spatial concentration in a dedicated detection zone.
As part of the system development, substantial effort was devoted to optimizing the synthesis and surface functionalization of polystyrene microparticles with silver nanostructures (PS@Ag), intended for future use as SERS-active carriers. Although surface-enhanced Raman spectroscopy (SERS) detection is not yet implemented, this study establishes the groundwork by demonstrating the feasibility of continuous particle focusing and transport within the microfluidic platform.
The presented device represents a crucial step toward the realization of an automated, flow-through analytical system, with the potential for future integration with separation techniques and real-time, SERS-based chemical analysis.
ACKNOWLEDGEMENT: This work was supported by the Czech Science Foundation (Grant No. 25-16617S). Additional support was provided by the ATEBIO project (ID CZ.02.01.01/00/23_020/0008535) funded by the European Union, and by institutional support RVO 68081715 from the Institute of Analytical Chemistry of the CAS (Czech Republic).

Quantum computing is currently emerging as a new computational technology for solving complex computational problems. Current quantum computers are unfortunately too noisy to provide sufficient accuracy, and quantum-classical hybrid algorithms emerged as a solution. Variational Quantum Algorithms are currently showing promising results at overcoming noise introduced by current level of quantum hardware. Variational Quantum Deflation (VQD) has gained significant attention when computing spectrum of eigenvalues in quantum chemistry and solid-state physics. Noise in VQD calculations performed on the current noisy quantum computers, or their simulators, can be partly suppressed by methods available in the Qiskit Python package provided by the IBM company. In our study, several of these error suppression and mitigation methods have been tested and our results offer rather unique comparison in the case of calculations of the electronic structure of crystals when the performance is sensitive to the actual point in the reciprocal space.
ACKNOWLEDGEMENTS: Financial supports from the Czech Academy of Science are gratefully acknowledged, in particular the Praemium Academiae awarded to MF, and the Strategy AV21 (the program "AI: Artificial Intelligence for Science and Society"). The authors further acknowledge financial supports from (i) The Ministry of Education, Youth and Sports via the INTER-EXCELLENCE II program, sub-program INTER-COST, in particular the project No. LUC25028, and (ii) the Quantum Innovation Centre providing us the access to the IBM quantum computers. Computational resources were provided by the Ministry of Education, Youth and Sports of the Czech Republic under the Projects e-INFRA CZ (ID:90254) at the IT4Innovations National Supercomputing Center and e-Infrastruktura CZ (e-INFRA LM2018140) at the MetaCentrum as well as CERIT Scientific Cloud, all provided within the program Projects of Large Research, Development and Innovations Infrastructures.

This theoretical study extends our previous calculations on Fe-doped hexagonal boron nitride (h-BN). We investigated the structural and thermoelectric properties of h-BN nanotubes when Fe atoms are introduced by substitution into the B sites. The objective is to evaluate the stability of the doped materials, their potential for harmful gas sensing, and their suitability for hydrogen-related applications through optimization of vibrational (IR and Raman) properties.
Calculations were performed on a (2 × 1 × 1) supercell using the SCF-LCAO-DFT-B3LYP approach implemented in the CRYSTAL17 program. The h-BN nanotubes were constructed from 2D hexagonal BN sheets, and doping configurations with one and two Fe atoms were considered. The obtained nanotubes exhibit semiconducting behavior. IR and Raman analyses reveal the active vibrational modes of (9,0) and (10,0) BN nanotubes, consistent with results from both the primitive and supercells. These findings support the feasibility of Fe-doped h-BN nanotubes for sensing and energy applications.

Graphitic carbon nitride (GCN) is a promising material in the field of photocatalysis. Mott-Schottky analysis and electrochemical impedance spectroscopy (EIS) were used to investigate the electronic structure and charge transfer properties of exfoliated GCN. The conduction band potential was measured by Mott-Schottky measurement and charge transfer kinetics were studied from Nyquist plots constructed from EIS measurements. Results from electrochemical measurements suggest, that exfoliation can be used to modify the electronic structure of GCN and potentially improve its photocatalytic properties.

Beyond their technological impact, 2D electron systems in semiconductor heterostructures provide a versatile platform for studying quantum many-body effects [1, 2]. A key feature is the ability to modulate the electron density into quasi-2D or 1D arrays, leading to rich physics. In a perpendicular magnetic field with a periodic superlattice, a 2D electron gas (EG) exhibits the fractal Hofstadter spectrum due to quantum interference [3, 4]. Embedding such systems in photon cavities (PCs) allows tunable control over electronic and material properties in chemistry [5], physics [6], and materials science [7]. The high polarizability and mobility of EGs in GaAs make them ideal for exploring strong coupling with far-infrared photons [8].
We have modeled a change in spin configuration in a 2D square array of quantum dots (QD) and rings (QR) subjected to a transverse magnetic field. The system is placed in a cylindrical far-infrared photon cavity with a circularly symmetric mode. Our simulations show that spin ordering in each QD or QR can be controlled by the electron-photon coupling strength and photon energy. Electron-electron interactions are treated within a spin-density functional framework, while para- and diamagnetic electron-photon couplings are handled using a configuration interaction approach in a truncated many-body Fock space. Without external pulses, spin reordering is reflected in the orbital magnetization of the rings and can be suppressed at strong coupling.
Dynamical simulations reveal spin fluctuations when the system is excited via a time-dependent coupling scheme that enhances the diamagnetic interaction [10].
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The magnetotransport and magnetooptical properties of an electron gas in a quasi-1D chain of planar quantum rings have been studied. The system was subjected to a homogeneous magnetic field directed perpendicularly to the plane of the structure. An analytic function for the external modulation potential is proposed to model the periodic motion of electrons in one direction and the quantized motion in the transverse direction of the structure. The basis vectors in the Hilbert space are chosen so that they capture both the symmetry and the periodicity of the system. The interaction between electrons is modeled in the Hartree approximation. The Rashba spin orbit interaction is also discussed. The computed electronic band structure as a function of the magnetic field reveals a high degeneracy in the spectrum of the system for specific values of magnetic field. The degeneracy is expressed as nodes in the energy minibands and has its signature in all the physical quantities discussed in the work. As a consequence, the orbital magnetization, and the longitudinal component of the magneto-conductance tensor exhibit oscillatory behavior which is sensitive to the Rashba coupling strength. For the transverse component of the conductance tensor plotted versus magnetic field induction, we observe a ladder-like behavior reminiscent of the quantum Hall effect. However, a detailed examination shows that the reason for such a behavior is the mini-band nodes. Additionally, we have calculated the magneto-absorption of the system within the dipole approximation. The absorption coefficient as a function of incident photon energy for two perpendicular photon polarizations and various magnetic field strengths has been analyzed.

The reliable detection of hydrogen sulfide (H₂S) at low concentrations is vital due to its toxicity and health hazards. In this work, we developed zinc stannate (Zn₂SnO₄, ZTO) thin films via a sol-gel spin coating process to serve as efficient H₂S gas sensors. The fabricated films, predominantly composed of Zn₂SnO₄ with a small fraction of ZnO, exhibited nanorods and hexagonal surface structures that significantly enhanced their sensing ability. Comprehensive structural and compositional analyses confirmed the crystalline quality and chemical purity of the films. Gas sensing tests revealed strong selectivity toward H₂S over other interfering gases. Notably, the sensors demonstrated a rapid response time of 10 seconds and recovery within 24 seconds when exposed to 7 ppm H₂S at an optimal operating temperature of 200 °C. The sensing behavior is explained through an adsorption-desorption mechanism, with intrinsic oxygen vacancies playing a crucial role in enhancing reactivity. These findings highlight the potential of nanostructured ZTO thin films as promising candidates for highly sensitive, selective, and fast-response hydrogen sulfide (H₂S) gas sensors.

Boron-doped diamond (BDD) thin films have emerged as multifunctional materials for advanced electronics due to their exceptional properties. When combined with gallium oxide (Ga₂O₃), a new class of heterostructures emerges that influences the complementary advantages of both materials, especially as next-generation power electronic (as p type) and optoelectronic devices (as n type). In this study, BDD films were synthesized on p-type silicon substrates using a microwave plasma-enhanced chemical vapor deposition system across a broad range of methane concentrations (1.5 % - 18 %) while maintaining a constant boron-to-carbon (B/C) ratio of 2000 ppm. Structural and physicochemical characterization using scanning electron microscopy, Raman spectroscopy, X-ray diffraction, and optical emission spectroscopy showed a distinct morphological evolution from microcrystalline diamond (1.5 % - 9% CH4) to nanocrystalline diamond (12 % - 15 % CH4), and further to two-dimensional needle-like pointed diamond structures at the highest methane concentration (18 %). The Hall effect analysis confirmed an enhancement in electrical conductivity with increasing methane content. Concurrently, Kelvin probe force microscopy measurements indicated a tunable work function ranging from 5.45 eV (1.5 % CH4) to 4.1 eV (18 % CH4).
As a proof-of-concept application, the as-grown BDD films were employed as multifunctional electrodes (n type) in microplasma display devices. BDD synthesized at 18% CH4 exhibited the lowest breakdown voltage (370 V) and the highest current density (36 mA cm-2), highlighting the strong influence of methane concentration on charge transport and optoelectronic performance. Furthermore, these findings provide an understanding of BDD tailoring via gas-phase chemistry and open a new avenue for underlining the significant potential of Ga₂O₃/BDD heterostructures for high-performance power electronics.

The structure and morphology of binary Ti-Si thin films were studied. Ti-Si surface alloys were deposited by electron beam. The Si content was controlled by the evaporation rate of Ti and Si targets. The structure was investigated by X-ray diffraction (XRD) and the morphology and surface roughness were measured by atomic force microscopy (AFM). The results show that the morphology and surface roughness reflect the structural evolution. The crystalline nature of Ti-Si thin films tends to nanocrystalline form. Higher amounts of Si resulted in an amorphous structure with a smoothed surface morphology and the lowest roughness.

The combination of inkjet-printing method and optical lithography was used to deposit multilayer sensing structure. Key advantages of inkjet printing include low material consumption, a quick transition from design to finished product, and low production costs. This is why this technology is increasingly used in the production of electronic circuits and devices. In contrast, metal sputtering in conjunction with optical lithography enables high-resolution patterning with excellent dimensional control and process repeatability, which are critical for the reliable fabrication of microscale features in microelectronic devices.
In this research, we present the formulation of an ink, including the synthesis of magnetoelectric nanoparticles (MENPs) and the preparation of a stable dispersion suitable for inkjet printing. Furthermore, we demonstrate the design, fabrication, and characterization of deposited magnetoelectric layers. MENPs are highly promising materials in the fields of nanotechnology, biomedicine, and spintronics due to their unique ability to interconvert electric and magnetic fields at the nanometer scale. The MENP-based ink was inkjet-printed onto both rigid and flexible substrates, and the resulting layers were characterized in terms of homogeneity, thickness, and particle distribution, considering different printing resolutions and numbers of overprinted layers, which are the main parameters that affect the final result. Scanning electron microscopy (SEM), optical microscopy, electrical measurements, and other analytical techniques were employed to evaluate the structural and functional properties of the printed layers.
This study provides a comprehensive approach to ink formulation, deposition, and characterization of magnetoelectric nanoparticle layers, offering valuable insights for the development of advanced multifunctional materials and additive techniques.

Cross-coupling reactions are fundamental to modern organic synthesis, enabling the rapid construction of carbon-carbon and carbon-heteroatom bonds. Merging photoredox catalysis with transition-metal catalysis has revolutionized these transformations, as visible light provides a sustainable means to access reactive metal oxidation states under mild conditions. While nickel and copper have been widely exploited in this dual-catalysis paradigm, the potential of cobalt remains largely underexplored. Here we report the first cobalt-mediated metallaphotoredox strategy for C(sp²)-S cross-coupling under visible-light irradiation. This approach enables the efficient coupling of diverse (hetero)aryl bromides, including challenging electron-rich substrates, with a broad range of thiol nucleophiles, delivering the corresponding products in yields up to quantitative. The operational simplicity, broad substrate scope, and sustainability of this protocol highlight cobalt as a powerful yet underutilized platform for dual-catalytic cross-coupling.

Metal-fullerene hybrid assemblies represent a specific class of materials exhibiting interesting properties [1, 2], which find their way into electronics [3], medicine [4], catalysis [5] or materials science [6]. However, due to the weak intermolecular interactions that bind the hybrid components together, the integrated assembly is thermodynamically unstable. Destructive processes, such as thermal annealing or ion irradiation, can lead to a change in their structure and consequently their properties.
In this work, the thermal stability of several nickel-fullerene complexes was investigated over a wide temperature range. The evolution of the samples was monitored using neutron depth profiling, Rutherford backscattering, micro-Raman spectroscopy and scanning electron microscopy. The results showed that the hybrid films exhibit a specific phase transformation upon heating, which leads to a dramatic change in their structure and culminates in the formation of a new self-assembled material.
REFERENCES: [1] J. Vacík et al., Pattern formation induced by co-deposition of Ni and C60 on MgO(100), Journal of Chemical Physics 114 (2001) 9115; [2] V. Lavrentiev et al., Emergent ferromagnetism and interface exchange bias in self-assembled copper-fullerene hybrid nanostructures, Advanced Composites and Hybrid Materials 8 (2025) 287; [3] M.G. Helanderat al., Metal/Fullerene Electrode Structure: Physics and Device Applications, Proc. SPIE 7051, Organic Light Emitting Materials and Devices XII, 70510Z (2 September 2008); [4] J. Vacik et al., Fullerene (C60) - Transitional Metal (Ni) Composites - Structural and biological properties of the thin films, Diamond and Related Materials 19 (2010) 242; [5] U.M. Dzhemilev et. al., Metal complex catalysis in the chemistry of fullerenes, Handbook on Fullerene: Synthesis, Properties and Applications, 2011, Ed. R.F. Verner, C. Benvegnu, 241-312; [6] P.A. Kumar et al., Fabrication and applications of fullerene-based metal nanocomposites: A review, Journal of Materials Research 36 (2021) 114.

This study focuses on the synthesis of poly(glycidyl methacrylate) (PGMA) using a mechanically controlled atom transfer radical polymerization (mechano-ATRP) activated by barium titanate (BaTiO3) or zinc oxide (ZnO) nanoparticles as piezoelectric agents. Polymerization optimizations were performed with a typical ATRP reaction mixture containing monomer, initiator, ligand, and transition metal. The piezoelectric agents were used at the amounts of 0.5 wt.% for ZnO and 4.5 wt.% for BaTiO3 nanoparticles. The presence of oxygen in the reaction mixture was minimized through argon purging. The mechano-ATRP was carried out in an ultrasonic bath under defined conditions, such as temperature and intensity, for 5 hours. The reaction kinetics were evaluated using proton nuclear magnetic resonance (1H NMR) by calculating monomer conversion over time. The polydispersity index and molar mass of the polymer were determined using gel permeation chromatography (GPC). The aim of this study was to gain control over the mechano-ATRP of PGMA to produce a well-defined polymer with a low polydispersity index, specifically below 1.4, which was successfully achieved.
ACKNOWLEDGEMENTS: The authors wish to thank the Czech Science Foundation (25-16538S) for financial support and also gratefully acknowledge the Ministry of Education, Youth and Sports of the Czech Republic - DKRVO (RP/CPS/2024-28/003).

Mechano-ATRP is newly discovered controlled polymerization technique, where the control of the reaction is provided by piezoactive component. The barium titanate particles were recognized as suitable additive to provide polymer chains with well controlled structure. The barium titanate particles can be obtained in both micro and nano dimensions. This study focuses on the investigation of effect of micro and nano size of barium titanate on the polymerization process of n-butyl acrylate. The reactions conditions including type of catalyst, ligand and piezoactive filler type and concentration were varied. Interestingly, the polymerization occurs only presence of the most active ligand, Me6Tren.
ACKNOWLEDGEMENT: The authors wish to thank the Czech Science Foundation (25-16538S) for financial support and also gratefully acknowledge the Ministry of Education, Youth and Sports of the Czech Republic - DKRVO (RP/CPS/2024-28/003).

Altermagnets attract ongoing interest because of their unexpected electronic properties, such as spin splitting of electron bands or various transport properties (anomalous and spin Hall effects). Besides the electronic properties, based on elementary excitations that can be classified using the electron spin as a good quantum number, attention has recently been paid to magnons, where such simple classification is not possible. Nevertheless, magnon-related properties of altermagnets are interesting as well, including the chirality-based splitting of magnon eigenvalues or various transport phenomena induced by temperature gradients. However, systematic description of these magnon-related properties is not available at present.
In this contribution, magnons in a simple model of altermagnetism, corresponding to a two-dimensional bilayer, are studied within the classical isotropic Heisenberg Hamiltonian. Particular attention is paid to the splitting of magnon eigenvalues as well as to the spin currents generated by temperature gradients. The obtained results are compared with those related to electrons, namely, with the spin splitting of electron eigenvalues and with the spin currents generated by external electric fields. It is found that the previously developed classification scheme [I. Turek, Physical Review B 106 (2022) 094432] is relevant for both electron-based and magnon-based properties; minor deviations are discussed as well.
ACKNOWLEDGEMENT: The work was supported financially by the Czech Science Foundation (grant No. 23-04746S).

Using the exciton-phonon Fröhlich interaction matrix elements for a core-shell quantum dot (QD), obtained in our earlier work [Comput. Mater. Sci., 246, 113394, 2025], we studied the Huang-Rhys parameter (HRP), which quantifies the strength of exciton-phonon coupling for a specific excitonic state. The phonon confinement effects and strong confinement regime for excitons are considered. The combined effect of the non-sphericity of the quantum dot core and the electron-hole exchange interaction on the exciton Huang-Rhys parameter in a QD with a zinc-blende structure has been studied for the first time. These effects remove the degeneracy of exciton energy levels, creating a fine structure. It is found that the non-sphericity affects only the 1U, -1U, 1L, and -1L exciton states. Calculations for the InP/ZnSe system show that for QDs with prolate and oblate cores, the HRP is larger than in the spherical case. The contribution of quasi-confined phonons to the HRP significantly exceeds that of interface phonons. The HRP also strongly depends on the ratio of light- to heavy-hole effective masses.
This work was supported by the HESC of MESCS RA within the framework of the research projects No. 24WS-1C040 and No. 21AG-1C048.

This study focuses on the optimization of the homopolymerization of glycidyl methacrylate (GMA) using atom transfer radical polymerization (ATRP). Particular attention was paid to the effect of reaction temperature on polymer nanostructure and the tendency of the epoxide ring to undergo undesired crosslinking reactions. Polymerizations were carried out at various temperatures (30-80 °C) while maintaining consistent reaction parameters. Nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC) were used for structural and molecular weight characterization. Results showed that elevated temperatures, particularly above 40 °C, led to increased crosslinking due to epoxy ring opening, which significantly affected the solubility and dispersity of the resulting polymers. The optimal reaction conditions were identified at lower temperatures (30-40 °C), where well-defined polymers with minimal crosslinking and narrow molecular weight distribution were obtained. Prepared polymers have been investigated using scanning electron microscope to see the size of the individual fabricated polymers. These findings highlight the importance of temperature control during ATRP of GMA to preserve epoxide functionality and ensure predictable polymer structure.
ACKNOWLEDGEMENT: 2/2 The authors wish to thank the Grant Agency of the Czech Republic (25-16538S ) for financial support and also gratefully acknowledge the Ministry of Education, Youth and Sports of the Czech Republic - DKRVO (RP/CPS/2024-28/003).