Modern Physics Letters B

Electron paramagnetic resonance (EPR) and optical absorption spectra of Mn²⁺ ions in alkali borotellurite glass systems have been studied. The EPR spectra of all the glass samples exhibit three resonance signals at g ≈ 2.0, g ≈ 3.3 and g ≈ 4.3. A six line hyperfine structure has also been observed at g ≈ 2.0. The concentration and temperature dependence of EPR signals were studied for Mn²⁺ ions in potassium borotellurite glass samples. The zero-field splitting parameter D has been calculated for different alkali borotellurite glass samples from the intensities of the allowed hyperfine lines. The paramagnetic susceptibility was calculated from the EPR data at various temperatures and the Curie constant was calculated from the 1/χ versus T graph. The optical absorption spectrum exhibits a single broad band near 498 nm and this has been attributed to the spin-allowed ⁵E_g → ⁵T_2g transition of Mn³⁺ ions in octahedral symmetry. The optical band gap energy (E_opt) and Urbach energy (Δ E) were calculated from their ultraviolet edges. The optical band gap energy varies between 3.38 and 3.61 eV and increases from Li to K glasses.

An electric-field assisted assembly has been used to place rod-shaped, metal-organic, molecule-metal nanowires onto lithographically defined metal pads allowing the electrical characterization of metal-molecule self-assembled monolayer-metal containing nanowires. Our results show that the parameters of metal-molecule metal junctions are close to previously published data, so we have constructed systems containing insulating monolayers with reasonable properties.

The surface structure of Pt/Si(001) has been studied using LEED and Low Energy Ion Scattering Spectroscopy (ISS). We find that the Pt coverages are saturated at 0.25 ML after annealing regardless of the initial coverages between 0.5 ~ 1.0 ML. We observe a c(4 × 2) image after annealing the Pt/Si(001) sample at 700°C and a clean c(4 × 6) image mixed with a clean c(4 × 2) image at annealing temperatures around 900°C. We find the structure of the Si(001) surface is changed due to Pt adsorption. The changed Si(001) surface still has the p(2 × 1) structure with increasing dimer length 0.6 Å

Based on a theoretical model proposed for an organic bipartite lozenge ferrimagnetic chain, the spin configuration of π electrons and the dimerization are investigated. With the Hartree–Fock approximation, the strong electron–phonon coupling and the electron–electron interaction in the one-dimensional system are taken into account self-consistently. It is shown that around the middle of the chain appears a π electron spin polarization cloud with alternation of sign and amplitude of the spin density extending over a certain distance, which extends all over the chain with no decay when the e–e interaction is larger than a critical value. In the stable ferrimagnetic state, the antiferromagnetic exchange interaction between electrons at site A and site B along the chain will become very strong, and almost zero dimerization happens for the chain.

Chen's lattice inversion method is expended to calculate the interatomic potentials of zinc-blend-type binary compounds with the virtual lattice technique, which proposes a scheme to obtain the non-empirical interatomic potentials based on the first principle calculation.

We investigate the temperature dependence of the penetration depth λ(T) in MgB₂ in the framework of the two-bands model using the Eliashberg formalism. We also study the influence of the impurities lifetime on the temperature dependence of λ(T). By direct comparison of the experimental data with theoretical results, a practical method to determine the orientation of the crystal is proposed.