Interpretation of the change in optical constants of different compositions of Ge–Se–In in terms of cohesive energy

Compositional dependencies of the optical and physical properties of as-deposited amorphous Ge_xSe_90?xIn₅ films (with 5≤x≤30 at%), prepared by thermal evaporation have been studied. The optical energy gap $E_g^{opt}$ is derived from Tauc's extrapolation in the strong absorption region in terms of transmission and reflection spectra. The relationship between the optical gap and chemical composition of the Ge_xSe_90?xIn₅ (with 5≤x≤30 at%) amorphous system is discussed in terms of the chemical bond approach. The refractive index, n and film thickness, d have been determined by an envelope method using transmission spectra. It is observed that the refractive index, n of Ge_xSe_90?xIn₅ thin films increases with increasing x, over the entire spectral range, which is related to both the increased density and average coordination number.     

The high-resolution FTIR spectrum of the ν4 + ν8 band of trans-d2-ethylene (trans-C2H2D2)

The FTIR absorption spectrum of the hybrid A–B type ν₄ + ν₈ combination band of trans-C₂H₂D₂ centered at 1845.98737 cm^?1 in the 1730–1940 cm^?1 region was recorded at an unapodized resolution of 0.0063 cm^?1. A total of 2725 a- and b-type transitions was assigned and fitted to upper state (ν₄ + ν₈ = 1) rovibrational constants up to sextic terms using Watson’s A-reduced Hamiltonian in I^r representation. The b-type feature of the band was analyzed for the first time. The root-mean-square deviation of the IR fit was 0.00059 cm^?1. The most accurate set of ground state rovibrational constants up to sextic terms was also derived from the simultaneous fit of 3340 ground state combination differences from the present analysis and the ν₄ band of trans-C₂H₂D₂. The transition dipole moment ratio $\left|\frac{{\mu }_a}{{\mu }_b}\right|$ was found to be 1.95 ± 0.06.     

YbNi2: A heavy fermion ferromagnet

Measurements of the magnetization and specific heat of YbNi₂ binary alloy are reported. The DC magnetic susceptibility displays a ferromagnetic behavior with a Curie temperature T_C=10.5 K, one of the highest found in Yb compounds. Moreover, the temperature dependence of the specific heat exhibits a lambda anomaly with a peak of 5.12 J/mol K at 9.4 K. The analysis also shows an additional magnetic contribution around 32 K stemming from the crystalline electric field of a quartet at ${\Delta }_1=72\mathrm{K}$ and a doublet at ${\Delta }_2=126\mathrm{K}$, according to the splitting of the Yb³⁺ ion in cubic symmetry. From the magnetic contribution to the specific heat, a relatively high Kondo temperature $T_K=27\mathrm{K}$ is estimated. Below the magnetic transition, the specific heat shows a huge value of the electronic coefficient ${\gamma }_{\mathit{LT}}=573\mathrm{mJ}/\mathrm{mol}\mathrm{K}$, which is a signature of a heavy fermion behavior. Therefore, this alloy is a fine example of enhanced ferromagnetism and heavy fermion behavior among Yb compounds.