Ion induced modification in structural and magnetic properties of Pt/Cr/Co multilayers

This paper reports on the change in the magnetic and the structural properties of Pt/Cr/Co multilayers due to 1 MeV N⁺-ion irradiation at room temperature. We observe irradiation induced formation of the CoCrPt ternary alloy phase at a fluence of 1×10¹⁶ ions cm^?2. Phase formation is accompanied by an enhancement in the coercivity. The enhancement in the coercivity is attributed to inhomogeneous alloying and possible mixing-induced strain. These findings are explained in the light of ion beam induced recoil mixing and ionization events.     

Interface study of Ag/57Fe/Ag trilayer using Mössbauer and X-ray standing wave analysis

Interface of Ag/⁵⁷Fe/Ag trilayer has been studied with a depth resolution of a fraction of a nanometer using x-ray standing waves generated by a W/Si multilayer mirror used as a substrate. Two interfaces of 38 Å thick Fe layer in Ag/⁵⁷Fe/Ag trilayer are clearly resolved. It is found that the rms roughness of the two interfaces Fe-on-Ag and Ag-on-Fe are 10 ± 1.0 and 6 ± 1.0 Å, respectively. Conversion electron Mössbauer spectroscopy (CEMS) has been used to get information about the volume fraction of the intermixed region and the estimated roughness from the relative area of the two sextets of CEMS spectra is found to be 7.0 Å which is consistent with the average roughness obtained by X-ray fluorescence measurements. However, the asymmetry of the interfaces can not be inferred from CEMS measurements.     

Depth-resolved fluorescence measurement in a layered turbid medium by polarized fluorescence spectroscopy

We show that, when a turbid medium with a layered fluorophore distribution is excited by linearly polarized light, measurement of angle-resolved polarized fluorescence can provide depth-resolved fluorescence measurements.     

Modes of vibrations due to (U-center + additive anion impurities) in KC1—II

Defect modes due to U-centers in potassium chloride containing additive anion impurities have been computed by Green's functions techniques. Local vibrations due to U-centers in alkali halides have cubic symmetry, but when one of the twelve nearest neighbour anions is replaced by an additive impurity, the site symmetry of the system reduces from O_h to C_2v and gives rise to new vibrational modes. The phonon Green's functions have been analysed according to the irreducible representation of the point group symmetry, pertaining to the substitutional impurity. We have considered the vibrations of the U-center, additive anion impurity and their nearest neighbours i.e. 36-dimensional defect space. Using group theory, symmetry coordinates were constructed and the 36 x 36 dimensional matrix was block diagonalised into various irreducible representations. The computed local mode frequencies have been conpared with the experimental measurements. Reasonably good agreement is found between them. The computed results for resonant mode frequencies are also displayed.     

Band structural properties of MoS2 (molybdenite)

Semiconductivity and superconductivity in MoS₂ (molybdenite) can be understood in terms of the band structure of MoS₂. We present here the band structural properties of MoS₂. The energy dependence of n_eff and ε_xeff is investigated. Using calculated values of n_eff and ε_xeff, the Penn gap has been determined. The value thus obtained is shown to be in good agreement with the reflectivity data and also with the value obtained from the band structure. The Ravindra and Srivastava formula has been shown to give values for the isobaric temperature gradient of $\text{E}{}_{\mathrm{G}}\text{[}\text{(?E}{}_{\mathrm{G}}\text{?T)}{}_{\mathrm{P}}\text{]}$, which are in agreement with the experimental data, and the contribution to $\text{(}\text{?E}{}_{\mathrm{G}}\text{?T)}{}_{\mathrm{P}}$ due to the electron lattice interaction has been evaluated. In addition, the electronic polarizability has been calculated using a modified Lorentz-Lorenz relation.     

Electrical conductivity studies of cobalt-precipitation in RbCl crystals

The results of electrical conductivity measurements in heavily doped RbCl:CoCl₂ crystals with 2500 and 6000 ppm of cobalt are being reported in this paper. The different regions of the conductivity plots for the crystals with the two concentrations of cobalt have been explained and relevant energy parameters determined. The crystals with 6000 ppm of cobalt have been found to contain two types of precipitates one of these being of the same type as that existing in RbCl crystals with 2500 ppm of cobalt while the other being of a different composition. Further, it has been found that the crystals appear blackened after heating during measurements. The blackening has been attributed to the expulsion of cobalt from the bulk of the crystal which forms an oxide at the surface.