Goethite is an antiferromagnetic material but has a superimposed magnetic component, known as weak ferromagnetism. An investigation with different samples and technics is presented. It has been shown with ESR results that this component can be enhanced or suppressed when morphological and structural properties are changed by annealing or use of different synthesis route.

The softening of W_x(TaTiVCr)_1−x is enhanced with higher temperature and lower W content. The influence of W content on both the heat capacity at constant volume (C_V) and at constant pressure (C_p) is very small. Thermo-entropy of W_x(TaTiVCr)_1−x rises with increasing temperature and lowering W content. The W–W bond of W_x(TaTiVCr)_1−x is stronger than W–M and M–M bonds (M = Ta, Ti, V, Cr).

Polycrystalline La₂Ni_1−xMn_1+xO₆ samples with different Ni:Mn ratio are prepared using sol–gel method. All samples are ferromagnetic in nature. Cation ordering is higher for Mn-rich samples. The LN75M125 sample shows largest saturation moment, Ms ≈5.65 μ_B/f.u.

TiO₂ slanted nanorods have been deposited by e-beam evaporation method utilizing glancing angle deposition technique on Si, glass, and FTO substrates. The structural evolution of nanorods is found to be controlled by the roughness of the substrates and nucleation centers present on the substrates. Annealing makes the TiO₂-slanted nanorods hydrophilic and the further UV irradiation modifies them to super-hydrophilic.

The magnetocaloric effect and the magnetic entropy (ΔS_M(T,H)) scaling around the magnetic transition temperature (T_C) have been investigated in two-dimensional ferromagnetic semiconductor CrGeTe₃ single crystal. The ΔS_M(T,H) under different magnetic fields can be scaled into a single curve independent of external field and temperature. The critical parameters n, l, and m have been obtained based on ΔS_M(T,H).

A polarization-insensitive and ultra-broadband metamaterial absorber (UMMA) is designed and demonstrated. The UMMA consists of alternately stacking Cu film and FR-4 dielectric layer. The calculation result shows that the UMMA's absorption rate is greater than 96% in the entire X-band (8–12 GHz). It can be applied in electromagnetic stealth, electromagnetic shielding and other fields.

In this work, the spin and electrical properties of armchair silicene nanoribbon in the presence of charged impurities are studied. Charged impurity is located in the underlying substrates. The spin diffusion length for different charge amplitudes is compared with the mean free path.

The modified superexchange model is used to obtain analytic expressions adapted to describe the nonresonance tunneling current across molecular wires, in which the current is mediated by terminal and interior repeating units of the wire. The analysis of the current–voltage characteristics of the alkane chain anchored to the electrodes by thiol groups shows a good agreement between the theory and the experiment.

In the present manuscript, the influence of rare earth substitution on the multiferroic properties of BiFeO₃ is investigated by preparing the compounds at the same level of substitution and under the similar synthesis conditions. This study is useful to estimate the potential of the substituent to tune the multiferroic properties of BiFeO₃ among other rare earth elements.

The operator formalism is briefly introduced for the three-level discrete jumping processes. This formalism is generalized to the non-Markovian case to discuss relaxation and internal-friction peak. Stretched exponential relaxation, namely, Kohlrausch–Williams–Watts function and internal frictions are obtained for a three-level discrete process. Results are numerically obtained. Figures are represented.

The stability of vacancy-carbon (v-C) clusters plays a key role in the post-irradiation damage recovery in steels. Therefore, the stability of v-C clusters in the presence of a solid solution background is essential. A model estimating the stability of v-C clusters in random solid solutions is presented. The model is parameterized for the Fe-Cr-C alloy using density functional theory.

Ternary chalcogenides Na₃SbX₄ (X = S, Se) are investigated by first-principles calculations based on density functional theory. The electronic and optical properties are computed to assess the superionic conductors and energy storage applications for development of visible-light harvesting materials. These chalcogenides have direct bandgap. The optical absorption is investigated by calculating dielectric functions, refractive index, and optical dielectric constant.

The structural parameters, elastic moduli, electronic structure, and optical properties of the ternary rhombohedral AEuS₂ (A = Na, K, Rb, and Cs) are reported. The mechanical stability of the AEuS₂ compounds is investigated, and the macroscopic elastic parameters are determined. It is shown that these crystals are indirect band gap semiconductors. The optical properties of the studied compounds are found to be anisotropic.

A detailed investigation regarding Stranski–Krastanov grown InAs and In_0.5Ga_0.5As quantum dots (QDs) is carried out. This study ascertains the cause of larger QD formation and better interface quality in case of In_0.5Ga_0.5As QD compared to the InAs QD. Hence, heterostructures with In_0.5Ga_0.5As QDs are useful for light-emitting diode and laser applications.

The structure and the electric, magnetic and thermoelectric properties of the magnetic nanocomposite Co/SiO₂ have been studied. Negative magnetothermoelectric power has been discovered. The explanation is related to the conductivity mechanism in the magnetic nanocomposite and its structure. It is shown that structural imperfections (such as defects in the Co nanocrystals, magnetic size distribution, phase intermixing) have additional impact on the magnetic properties.

Substitutional doping of H-phase single-layer CrS₂ at S-site with a nonmetal atom, such as B, C, N, P, As, O, or F, is investigated through first-principles calculations within the framework of spin-polarized density functional theory. The results reveal that the electronic and magnetic properties of single-layer CrS₂ can be effectively modulated via nonmetal atoms.

Extended X-ray absorption fine structure (EXAFS) analysis of the nearest neighbor environment in kesterite Cu₂ZnSn(S_xSe_1–x)₄ alloys is presented. Bimodal behavior of the cation–anion distances is observed for the metal–sulfur and metal–selenium bonds. Differences in the static disorder around the metal atoms are noted.

The effect of Mn_100−xGe_x composition (for x = 20, 25, 30) on phase formation, electronic structure, and magnetic properties of polycrystalline Mn–Ge alloys is investigated. The structural analysis in agreement with electronic structure calculations and optical data suggests that Mn–Ge undergoes a tetragonal (T) to orthorhombic (O) transition in this composition range, which significantly alters the magnetic properties of these alloys.

Lorentz microscopy experiments reveal the suppression of the stripe-to-bubble transition through application of magnetic fields perpendicular to hexaferrite PbFe₁₂O₁₉ thin plates. By contrast, zero-field stabilized magnetic bubbles can be generated after in-plane field treatment. In situ heating experiments reveal the metastable nature of zero-field bubbles and the facilitating role of Bloch lines in stripes for forming magnetic bubbles.

The path-integral Monte Carlo simulations show significant quantum effects in cubic boron nitride (c-BN). The analyses on the atomic vibrational energy, zero-point motion, and root-mean-square displacement (RMSD) indicate that c-BN is essentially an anharmonic quantum crystal below 1000 K.

Oxygen doping makes MgCl₂ electrochemically active because of strong interaction with Li. The bulk and monolayer deliver high Li specific capacities of 941 and 1098 mAh g⁻¹, respectively. The diffusion barrier for the bulk is calculated to be 0.6 eV. O doping may be achieved by O annealing because of a low reaction enthalpy.

Density functional theory calculations are applied to study covalent interactions between inorganic diamond nanoparticles (nanodiamonds, ND) and organic-conjugated polymer polypyrrole (PPy) for photovoltaic applications. Spatially separated highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) obtained for a considerable number of the PPy–ND structures are favorable for exciton dissociation. The figure is the example of spatially separated HOMO and LUMO in physisorbed structure with indicated electron excitation from PPy to ND.

Single crystal kesterite Cu_2−xZnSnSe₄ are grown over a wide range of Cu/(Zn + Sn) compositions in quasi-equilibrium without fluxing agents. Van der Pauw resistivity provides majority carrier concentration and mobility. Hot probe voltage provides the Seebeck coefficient used to determine the valence band density of states. Optical band gap and temperature-dependent conductivity are determined for a crystal subset.

The TM atom (Cr, Mn, Fe, Co, or Ni) doped CdSNSs results in spin-polarized states with the preservation of its direct band gap character. The magnetism of doped CdSNSs is mainly attributed to the TM atom with a strong localized magnetic moment. The red-shift phenomenon is found in low-energy region.

BiOX–YO₃ (X = Cl, Br, I; Y = Mo, W) heterostructures exhibit good absorption in the visible light region. The electron effective masses of the BiOI–YO₃ heterostructures, especially BiOI–WO₃, are lower than those of the YO₃ monolayer components. Besides, the valence band maximum (VBM) and conduction band minimum (CBM) of BiOX–YO₃ are separate and reside in the BiOX and YO₃ layers, respectively.

The properties of both graphene and GeS are preserved in the van der Waals (vdW) heterostructure, which is advantageous for improving photocatalytic efficiency. Additionally, the vdW heterostructure shows increased spontaneous polarization and controllable Schottky barrier height. The compressive strain can have a significant impact on both the spontaneous polarization and the energy barrier height of the vdW heterostructure.

The network structure of MgSiO₃ glass consists of SiO_x and MgO_y units. These units link to others by corner-, edge- and face-sharing bonds. Tension tests are performed on this glass. The stress–strain curves exhibit the elastic and plastic characteristics. The formation of shear transformation zones occurs in the plastic region. Shear band is observed at the strain of 0.82.

A photonic crystal (PC) cavity with high quality factor, wide measurement range, and high refractive index sensitivity is proposed. Combined with the gas sensitive characteristics of cholesteric liquid crystal (CLC) and the resonance characteristics of the PC cavity, this proposed PC cavity can be theoretically used for tetrahydrofuran vapor sensing.

Below-band-edge excitation leads to thermal expansion, followed by electron–hole liquid (EHL) formation in monolayer MoS₂. The initial excitation is to the near edge defect states. As the material heats, the band gap tunes and excitation photons become resonant, creating enough density of excitons for ionization and EHL condensation.

As shown by first-principles calculations, the electronic properties of MoSSe/WX₂ (X = S and Se) van der Waals heterostructures can be tuned by an electric field and mechanical strain.

On the SrTiO₃(110) surface, a series of reconstructions are created via repeated cycles of argon ion sputtering and annealing. These reconstructions are studied with scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). Typical structural units in the reconstructed surface are identified. Meanwhile, the combination of STM and LEED eliminates the interference from the coexisting multiple structures.

The effect of threading dislocations, V-defects and clusters of V-defects on the electrical properties of AlN on Si {111} was studied. Threading dislocations have the largest impact on electrical properties of AlN due to their high density and uniform distribution. The impact of V-defects and their clusters is lower because of localized nature of these defects.

Hexagonal boron carbon nitride (BC₂N), an indirect bandgap semiconductor with brittle manner, has a hardness of 70 GPa. All elastic constants and elastic modulus are positively correlated with the modulation of the external forces, while the situations in Vicker's hardness are much more complicated. Moreover, anisotropic properties, as well as the Debye temperature are also discussed.