arXiv subjects

F. J. Manjon

Publications and source records attributed to F. J. Manjon.

21 records · Page 2Linked to original sources

arXiv2004

Effect of isotopic mass on the photoluminescence spectra of beta zinc sulfide

Zinc sulfide is a wide bandgap semiconductor which crystallizes in either the wurtzite modification (a-ZnS), the zincblende modification (b-ZnS) or as one of several similar tetrahedrally coordinated polytypes. In this work, we report a photoluminescence study of different samples of isotopically pure b-ZnS crystals, and crystals with the natural isotopic abundances, at 15 and 77 K. The derivatives of the free and bound exciton energies on isotopic mass have been obtained. They allow us to estimate the contribution of the zinc and sulfur vibrations to the bandgap renormalization energy by electron-phonon interaction. A two-oscillator model based on the zinc and sulfur renormalization energies has been used to account for the temperature dependence of the bandgap energy in ZnS. The results are compared with those found for other tetrahedrally coordinated semiconductors.

cond-mat.mtrl-sci↗

arXiv2004

Effects of pressure on the local atomic structure of CaWO4 and YLiF4: Mechanism of the scheelite-to-wolframite and scheelite-to-fergusonite transitions

The pressure response of the scheelite phase of CaWO4 (YLiF4) and the occurrence of the pressure induced scheelite-to-wolframite (M-fergusonite) transition are reviewed and discussed. It is shown that the change of the axial parameters under compression is related with the different pressure dependence of the W-O (Li-F) and Ca-O (Y-F) interatomic bonds. Phase transition mechanisms for both compounds are proposed. Furthermore, a systematic study of the phase transition in 16 different scheelite ABX4 compounds indicates that the transition pressure increases as the packing ratio of the anionic BX4 units around the A cations increases.

cond-mat.mtrl-sci↗

arXiv2003

Modellization of RGB lasers based on QPM structures with independent control of laser intensities by electrooptic effect

Recently simultaneous generation of continuous-wave visible laser light in the three fundamental colors has been experimentally demonstrated in Nd3+-doped LiNbO3 and Sr0.6Ba0.4(NbO3)2 by quasi-phase matching intracavity self-frequency conversion. In this work, we report the modelization of RGB lasers operating under similar experimental conditions but designed in the simplest quasi-periodically poled ferroelectric form by using the Fourier Transform technique. The aim of this work is to analyse the possibility of controlling the three laser intensities in an independent and novel way by means of the linear electrooptic (Pockels) effect in these non-linear materials. Our results suggest that the application of electrooptic effect for this purpose, according to our proposed scheme, is better adapted to Sr0.6Ba0.4(NbO3)2 than to Nd3+-doped LiNbO3.

cond-mat↗