Formation of bubble lattices stable at remanence at room temperature is investigated in epitaxial [Re(1 nm)/ Co(d(Co))/Pt(1 nm)](20) multilayers with thickness of the Co component layer, d(Co), ranging between 0.8 nm and 2.0 nm. Due to asymmetric neighbourhood of heavy metal slabs (Pt and Re) with ferromagnetic layers (Co) the interfacial Dzyaloshinskii-Moriya interaction occurs in this system in addition to perpendicular magnetic anisotropy. It substantially affects the observed domain structure. The domain structure with perpendicular magnetization still can be observed for Q < 1 (where Q is a quality factor equal to ratio of uniaxial anisotropy to demagnetization energy). We study evolution of the domain structure at remanence depending on the sample magnetic history described by: (i) applied field inclination angle and (ii) the field strength. The bubble lattice appears only in a narrow field inclination angle range, taking a specific value for selected d(Co). With increase in d(Co) (decrease in Q) this specific field orientation rotates from parallel to perpendicular direction relative to the sample plane. The maximum density of the bubble lattice reaches a level of 19 & micro;m(-2). Interpretation of the experimental results is supported by micromagnetic modelling taking into account measured strengths of perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya interaction. The modelling reproduces domain structure and numerous parameters characterizing the bubbles found in experiment. It also allows to get an insight into internal spin structure of the bubble walls. The obtained results suggest that the developing bubbles are topologically protected skyrmions.

Au-catalyzed CdO nanowires with well-defined morphology and single-crystalline structure.

The aim of this study was to sonochemically synthesize SnS and SnS2 quantum dots modified in situ with organic dye. For this purpose Rhodamine B, a dye from the xanthene group, is used. The resulting nanomaterials were characterized with the following techniques: X-ray powder diffraction, XPS, Raman and EDX spectroscopic techniques to confirm the production of desired compounds. HR-TEM observations prove the formation of quantum dots while the Tauc method was used to study the optical energy bandgap of both modified and unmodified nanomaterials. Raman studies showed not only that nanometric samples of SnS and SnS2 were obtained, but the recorded fluorescence from Rhodamine B indicates the presence of its molecules on the surface of these nanoparticles. The modification with Rhodamine B preserved the morphology and phase composition of tin sulphides but caused the occurrence of additional electron transitions as revealed by Tauc analysis. The contact angle measurements showed increase and decrease of contact angle due to modification with dye, for SnS2 and SnS respectively. The photo- and sonocatalytic activities of both modified and unmodified quantum dots are studied and compared, including kinetic analyses, investigations of influence of degree of functionalization and catalyst's amount, and determination of reactive intermediates (scavenging experiments). The modification of SnS with Rhodamine B improved it's sono- and photocatalytic activity. The investigation of the best catalyst after 5 cycles of sonocatalytic process showed it's oxidation to SnO2. Scavenging experiments revealed that the main reactive intermediate in the case of SnS with optimized amount of dye was radical anion •O2-. Finally, the n-th order kinetic model provided the most accurate description of photocatalytic processes.

Encapsulation within single-walled carbon nanotubes (SWCNTs) provides a route to stabilize quasi-1D confined halide fragments derived from layered NiCl2 and to tune their electronic and magnetic responses. Here we combine high-resolution STEM/EDS and spin-polarized DFT + U calculations to examine NiCl2 fragments confined inside metallic (11,11) SWCNTs. Encapsulated NiCl2 forms structurally continuous confined fragments derived from the layered NiCl2 motif, consistent with the extended filling observed experimentally, in which the collinear FM configuration is energetically preferred (0 K) within the strongly confined (11,11) reference model, while larger diameters bring FM and AFM closer in energy (and can favor AFM), in contrast to antiferromagnetic bulk NiCl2 (see SI). Spin-resolved PDOS and band analyses indicate that the pronounced Ni 3d spin-down peak at the Fermi level originates from weakly dispersive states, while CNT it-derived bands contribute the dominant delocalized channels at charge neutrality. Transport metrics suggest a confinement-related DOS-velocity mismatch that suppresses spin-down transport tendencies at neutrality while enabling increased spin-down contribution under modest chemical-potential shifts (approximate to+0.1-0.2 eV). Our results suggest that NiCl2@SWCNT provides a case study for exploring how confinement tunes magnetic competition and spin-dependent transport tendencies in low-dimensional halide guests.

This work describes the synthesis and properties of a magnetic composite material composed of magnetite (Fe3O4) and polyazulene (PAZ). The material was synthesised under chemical conditions. The morphology and properties of synthesised materials heavily depend on synthesis conditions, such as monomer concentration, Fe3O4 amount used in the synthesis procedure, as well as time and temperature of polymerisation. The obtained composite material demonstrated better electrochemical performance than the pristine polymer. The use of a magnetic working electrode ensures high stability under electrochemical conditions. The composite material exhibits its highest electrochemical stability in an acetonitrile solution. The capacitance in this solvent was studied, which ranged from 34 to 130 F g-1 and changed depending on the synthesis conditions. The highest specific capacitance values obtained were 130 F g-1 and 377 F g-1 based on the composite and polymer mass, respectively. These values were approximately seven times higher than those of pristine polymeric material.

Crystals under one-dimensional (1D) confinement are well-known to exhibit drastic changes in metallicity, magnetic properties and chemical state, however, the intermediate phase space between binary metal halides and ternary metal halide perovskites remains poorly explored, especially in the context of the rich polymorphism exhibited by both families in the one-dimensional limit. Through aberration-corrected (scanning) transmission electron microscopy and multislice simulations, it is shown that the metal halide Cs_2CoCl_4 crystallizes in the tetragonal ℘4/mcc and orthorhombic ℘mcm rod groups under radial compression within single-walled carbon nanotubes (SWCNTs) of increasingly small diameter, with a massive re-entrant orthorhombic strain towards the 1 nm extremum. The persistence of Co^2+ is determined from fits to the d.c. magnetization, with a surprisingly small increase in the effective moment (4.607(3) to 4.788(3) μ_B/f.u.) and Weiss constant (-7.9(3) to -4.09(7) K) after confinement in the SWCNTs, suggesting that the confined structure topologically preserves the core magnetic properties of the bulk. Both unconventional polymorphs observed are noticeably different to the high-pressure piezochromic polymorph previously shown to undergo a tetrahedral-to-octahedral coordination transition, highlighting 1D confinement as a unique tool for structural manipulation.

Developing efficient ammonia synthesis catalysts is key to reducing energy consumption and improving sustainability. This study explores barium-promoted cobalt catalysts supported on lanthanide oxides (La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3) to understand how support choice influences catalytic performance. The catalysts were characterised using techniques such as X-ray powder diffraction (XRPD), high-resolution transmission electron microscopy (HRTEM), and temperature-programmed desorption (H2-TPD, CO2-TPD). Testing under industrially relevant conditions (400-470 degrees C, 6.3 MPa, H2/N2 = 3) revealed that lanthanide oxides strongly affect catalysts' activity, reducibility, and hydrogen adsorption. Among the tested catalysts, the La2O3-supported system exhibited the highest ammonia synthesis activity (ravg = 1.90gNH3 center dot g-cat 1 center dot h-1), likely due to its favorable hydrogen sorption properties and larger active phase surface area available for hydrogen (31 m2 & sdot;gCo-1). These findings highlight the potential of lanthanide oxides as supports and the importance of barium as a promoter in cobalt-based catalysts for ammonia synthesis.

Implantation of the (110)-oriented surfaces of CdTe single crystals, chemically polished in a bromine-ethylene glycol-dimethylformamide solution, with 500 keV Cr+ ions at fluences of 10(16), 10(17), and 5 & sdot;10(17) cm(-2) was performed. Investigations using various experimental methods showed that implantation significantly alters the surface morphology, structure, and phase composition, depending on the applied fluence. Upon ion bombardment, the surface topography becomes coarser and rougher, evolving into a highly eroded pattern at the highest fluence due to prolonged irradiation-induced sputtering. In parallel, an improvement in surface crystallinity was observed after removal of the amorphous, tellurium oxide-enriched top layer formed during polishing. Structural disordering and precipitation of Cr-Te phases were detected in the near-surface layer as the fluence increased to 5 & sdot;10(17) cm(-2). This behavior is attributed to a shift of the surface toward the region of damage buildup and dopant aggregation, induced by irradiation under sputter equilibrium conditions. However, even at the highest dose, no amorphization was observed, suggesting that the CdTe lattice is highly resistant to degradation under bombardment by medium-energy Cr+ ions. The results demonstrate the potential of ion implantation for fabricating a composite consisting of a CdTe semiconducting matrix with embedded Cr-Te ferromagnetic nanoprecipitates, which could have spintronic applications.

The influence of Re layer insertion either at the bottom or top interface of epitaxially grown Pt/Co/Pt heterostructures on their static and dynamic magnetic properties is discussed in terms of their crystalline structure. Magnetic properties were studied as a function of both Re and Co layer thicknesses (d(Re) and d(Co), respectively) in the matrix-like samples with a double-wedge structure, in which the layer thickness gradients were oriented orthogonally. The comprehensive investigations of the changes in coercivity, perpendicular magnetic anisotropy, spin reorientation transition, interfacial Dzyaloshinskii-Moriya interaction (iDMI) and spin wave damping are reported. Two different magnetic phases depending on the Co layer thickness with volume anisotropies (determined without demagnetization term) of K-V similar to 0.25 (low) and K-V similar to 0.75 MJ/m(3) (high) were observed. The relation between these phases depends on the stack sequence and thickness of Re inserted layer. For d(Re) = 0.2 divided by 0.7 nm deposited as the bottom interface, d(Co) induced transition at d(tr) similar to 2 nm from low to high volume anisotropy phases was observed. Low and high volume anisotropy phases are associated to Co fcc and hcp structural phases. The insertion of half atomic layer of Re had no influence on surface anisotropy but significantly enhanced iDMI above 1 pJ/m and reduced spin wave damping.

In situ Eu-doped ZnCdO-ZnMgO superlattices with varying ZnCdO:Eu and ZnMgO sublayers thicknesses were deposited by plasma assisted molecular beam epitaxy.

We investigate epitaxial $\text{Co}(20 \, \text{Å})$ and $\text{Co}_{1-x}\text{Au}_{x}(20 \, \text{Å})$ alloy thin-films surrounded by asymmetric heavy metals layers of $\text{Re}(10 \, \text{Å})$ as a buffer and $\text{Pt}(30 \, \text{Å})$ as a cap to study the magnetic anisotropy, interfacial Dzyaloshinskii-Moriya interaction (iDMI) and damping. The increase of Au from 0% to 25% in the $\text{Co}_{1-x}\text{Au}_{x}$ alloy generates the spin-reorientation transition of around 13% of Au. The increase in Au concentration provides a significant decrease in saturation magnetization from 1690 kA/m to 982 kA/m measured for Co and $\text{Co}_{75}\text{Au}_{25}$, respectively. The effective anisotropy constant $\text{K}_{eff}$ is elevated up to 0.33 $\text{MJ/m}^{3}$ by changing the Au content. Further, our investigations of the magnetization dynamics have confirmed that the overall effective damping constant rises with the Au concentration which can be attributed to the spin pumping effect. The spin pumping leads to the highest value of effective spin mixing conductance $g^{(\uparrow \downarrow)} \approx 2.91 \times 10^{18} \, \text{m}^{-2}$ in the $\text{Co}_{90}\text{Au}_{10}(20 \, \text{Å})$ system, while the lowest value of $g^{(\uparrow \downarrow)} \approx 2.25 \times 10^{18} \, \text{m}^{-2}$ is found for the $\text{Co}(20 \, \text{Å})$ system. Additionally, we have investigated the iDMI strength, and the amplitude of iDMI decreases with increasing Au concentration. The highest surface iDMI constant value equal to 2.62 pJ/m is observed for Co.

We investigate epitaxial Co(20 Å) and Co_1-xAu_x(20 Å) alloy thin-films surrounded by asymmetric heavy metals layers of Re(10 Å) as a buffer and Pt(30 Å) as a cap to study the magnetic anisotropy, interfacial Dzyaloshinskii-Moriya interaction (iDMI) and damping. The increase of Au from 0 generates the spin-reorientation transition of around 13 in Au concentration provides a significant decrease in saturation magnetization from 1690 kA/m to 982 kA/m measured for Co and Co_75Au_25, respectively. The effective anisotropy constant K_eff is elevated up to 0.33 MJ/m^3 by changing the Au content. Further, our investigations of the magnetization dynamics have confirmed that the overall effective damping constant rises with the Au concentration which can be attributed to the spin pumping effect. The spin pumping leads to the highest value of effective spin mixing conductance g^(↑↓)≈ 2.91 × 10^18 m^-2 in the Co_90Au_10(20 Å) system, while the lowest value of g^(↑↓)≈ 2.25 × 10^18 m^-2 is found for the Co(20 Å) system. Additionally, we have investigated the iDMI strength, and the amplitude of iDMI decreases with increasing Au concentration. The highest surface iDMI constant value equal to 2.62 pJ/m is observed for Co.

{CdO/ZnO}m superlattices (SLs) have been grown on c-plane sapphire substrates by plasma-assisted molecular beam epitaxy (PA-MBE). The observation of satellite peaks in the XRD studies of the as-grown and annealed samples confirms the presence of a periodic superlattice structure. The properties of as-grown and annealed SLs deposited on c-oriented sapphire were investigated by transmission electron microscopy, X-ray diffraction and temperature dependent PL studies. The deformation of the SLs structure was observed after rapid thermal annealing. As the thermal annealing temperature increases, the diffusion of Cd ions from the quantum well layers into the ZnO barrier increases. The formation of CdZnO layers causes changes in the luminescence spectrum in the form of peak shifts, broadening and changes in the spacing of the satellite peaks visible in X-ray analysis.

In this paper we present a synthesis and characterization of cerium(IV) oxide (CeO2) micropowders under four different synthetic conditions and their evaluation as photo- and sonocatalysts in the process of degradation of model azo-dye Metanil Yellow. The powders were prepared by precipitation method at two different temperatures (20 and 80 degrees C). Two compounds (cerium(III) acetate and cerium(IV) ammonium nitrate) were used as starting reagents. The products were characterized by following techniques: X-ray powder diffraction, scanning and transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, Tauc method, Raman spectroscopy, shape analysis, and N2 physisorption measurements. All prepared CeO2 powders showed occurrence of two direct and one indirect transitions. The values of optical energy bandgap for direct transitions were redshifted and typically were placed in the range 2.62-3.83 eV. According to the XRD studies, nanocrystallites of the size 2.9-5.5 nm were present in samples prepared from (CH3COO)3Ce at 80 degrees C and from (NH4)2Ce(NO3)6 at 20 degrees C. Additionally, the HR-TEM observations revealed the presence of nanocrystallites of distinct sizes in all produced samples. The obtained CeO2 powders were studied as sono- and photocatalysts in the process of removal of Metanil Yellow from aqueous solutions by ultrasound and ultraviolet radiation. The CeO2 powder synthesized at 80 0 C from (CH3COO)3Ce as the starting compound exhibited the best sono- and photocatalytic activities in the removal of Metanil Yellow. The decrease in dye concentration was 28.43 mg/L and 25.65 mg/L after 120 min of photo- and sonodegradation, respectively. It turns out that the catalytic activity of the best sample was supported by its defection with Ce3+ cations and by textural properties (specific surface area).

A sonochemical synthesis of SnS2 quantum dots using acetone as a solvent is investigated. Two different tin sources (SnCl2∙2H2O or SnCl4∙5H2O) as well as two different sulfur sources (thioacetamide or Na2S2O3) were applied. The sonication time was also varied between 60 and 120 min. Resulting products of syntheses were characterized with the following techniques: powder X-ray diffraction, electron microscopy (SEM and HR-TEM), Raman and FT-IR spectroscopies, the Tauc method, and X-ray photoelectron spectroscopy. Obtained SnS2 nanostructures were in the form of quantum dots in the case of synthesis lasting 60 min (size of crystallites in the range of 3.5–7 nm) and in the form of elongated nanorods of length ca. 25–30 nm and width of 5–6 nm in the case of synthesis lasting 120 min. XPS analyses revealed that the surface of the obtained products contained a significant amount of tin at the second oxidation state (i.e., SnS). The quantum dots produced in the synthesis lasting 60 min showed a value of energy bandgap of 2.7 eV indicating potential applications in photocatalysis.

The recent discovery of superconductivity in infinite layer thin films and bulk Ruddlesden-Popper nickelates has stimulated the investigation of other predicted properties of these materials. Among them, the existence of magnetism-driven ferroelectricity in the parent compounds RNiO3 (R = 4f lanthanide and Y) at the onset of the N & eacute;el order, T-N, has remained particularly elusive. Using diffraction techniques, we reveal here the existence of magnetostriction at T-N in bulk YNiO3 single crystals. Interestingly, the associated lattice anomalies are much more pronounced along the b crystal axis, which coincides with the electric polarization direction expected from symmetry arguments. This axis undergoes an abrupt contraction below T-N that reaches Delta b/b similar to -0.01%, a value comparable to those found in some magnetoresistive manganites and much larger than those reported for magnetism-driven multiferroics. This observation suggests a strong spin-lattice coupling in these materials, consistent with theoretical predictions. Using the symmetry-adapted distortion mode formalism, we identify the main ionic displacements contributing to the lattice anomalies and discuss the most likely polar displacements below T-N. Furthermore, our data support symmetric superexchange as the most likely mechanism responsible for the magnetoelastic coupling. These results, that may be common to the full RNiO3 family, provide new experimental evidence supporting the predicted existence of magnetism-driven ferroelectricity in RNiO3 perovskites.

We investigate epitaxial Co(20 Å) and Co1-xAux(20 Å) alloy thin-films surrounded by asymmetric heavy metals layers of Re(10 Å) as a buffer and Pt(30 Å) as a cap to study the magnetic anisotropy, interfacial Dzyaloshinskii-Moriya interaction (iDMI) and damping. The increase of Au from 0% to 25% in the Co1-xAux alloy generates the spin-reorientation transition of around 13% of Au. The increase in Au concentration provides a significant decrease in saturation magnetization from 1690 kA/m to 982 kA/m measured for Co and Co75Au25, respectively. The effective anisotropy constant Keff is elevated up to 0.33 MJ/m3 by changing the Au content. Further, our investigations of the magnetization dynamics have confirmed that the overall effective damping constant rises with the Au concentration which can be attributed to the spin pumping effect. The spin pumping leads to the highest value of effective spin mixing conductance g(↑↓)≈2.91×1018/m2 in the Co90Au10(20 Å) system, while the lowest value of g(↑↓)≈2.25×1018/m2 is found for the Co(20 Å) system. Additionally, we have investigated the iDMI strength, and the amplitude of iDMI decreases with increasing Au concentration. The highest surface iDMI constant value equal to 2.62 pJ/m is observed for Co.

High-resolution transmission electron microscopy and superconducting quantum interference device magnetometry shows that epitaxial CuMnSb films exhibit a coexistence of two magnetic phases, coherently intertwined in nanometric scales. The dominant alpha phase is half-Heusler cubic antiferromagnet with the N & eacute;el temperature of 62 K, the equilibrium structure of bulk CuMnSb. The secondary phase is its ferromagnetic tetragonal 9 polymorph with the Curie temperature of about 100 K. First principles calculations provide a consistent interpretation of experiment, since (i) total energy of 9-CuMnSb is higher than that of alpha-CuMnSb only by 0.12 eV per formula unit, which allows for epitaxial stabilization of this phase, (ii) the metallic character of 9-CuMnSb favors the Ruderman-Kittel-Kasuya-Yoshida ferromagnetic coupling, and (iii) the calculated effective Curie-Weiss magnetic moment of Mn ions in both phases is about 5.5 mu B, favorably close to the measured value. Calculated properties of all point native defects indicate that the most likely to occur are MnCuantisites. They affect magnetic properties of epilayers, but they cannot induce the ferromagnetic order in CuMnSb. Combined, the findings highlight a practical route towards fabrication of functional materials in which coexisting polymorphs provide complementing functionalities in one host.

$\alpha$-Sn is an elemental topological material, whose topological phases can be tuned by strain and magnetic field. Such tunability offers a substantial potential for topological electronics. However, InSb substrates, commonly used to stabilize $\alpha$-Sn allotrope, suffer from parallel conduction, restricting transport investigations and potential applications. Here, the successful MBE growth of high-quality $\alpha$-Sn layers on insulating, hybrid CdTe/GaAs(001) substrates, with bulk electron mobility approaching 20000 cm$^2$V$^{-1}$s$^{-1}$ is reported. The electronic properties of the samples are systematically investigated by independent complementary techniques, enabling thorough characterization of the 3D Dirac (DSM) and Weyl (WSM) semimetal phases induced by the strains and magnetic field, respectively. Magneto-optical experiments, corroborated with band structure modeling, provide an exhaustive description of the bulk states in the DSM phase. The modeled electronic structure is directly observed in angle-resolved photoemission spectroscopy, which reveals linearly dispersing bands near the Fermi level. The first detailed study of negative longitudinal magnetoresistance relates this effect to the chiral anomaly and, consequently, to the presence of WSM. Observation of the $\pi$ Berry phase in Shubnikov-de Haas oscillations agrees with the topologically non-trivial nature of the investigated samples. Our findings establish $\alpha$-Sn as an attractive topological material for exploring relativistic physics and future applications.