Hamburg 2001 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 24: Poster II

HL 24.89: Poster

Donnerstag, 29. März 2001, 10:30–19:00, Rang S\ 3

Electric field gradients in chalcogenide spinels studied by ¹¹¹In(¹¹¹Cd) - PAC — •I. Burlacov¹, V. Samokhvalov¹, S. Unterricker¹, M. Dietrich², I. Tiginyanu³, and ISOLDE - Collaboration⁴ — ¹Institut für Angewandte Physik, TU Bergakademie Freiberg, D-09596 Freiberg/Sachsen — ²Fachbereich Physik, Universität Konstanz, D-78457 Konstanz — ³Technical University of Moldova, 2004 Chisinau, Moldova — ⁴CERN-Geneva, Switzerland

Several chalcogenide spinels with the general formula AB₂X₄ (where A= Cd or Hg, B= In or Cr, and X= S or Se) have been investigated by perturbed angular correlations (=PAC), which is a nuclear spectroscopic method. Thereby the axially symmetric electric field gradient (EFG) at B-site of the crystal lattice could be determined. We used ¹¹¹In(¹¹¹Cd) radioactive probes implanted at the Rossendorf cyclotron or at the ISOLDE-CERN (Geneva) on-line implanter. A strong preference of the B-site occupation was observed. Measurements at elevated temperatures revealed a linear dependence of the EFG in a wide temperature range in all spinels under consideration. The theoretical values of EFG calculated by the WIEN 97-code /1/ have been compared with experimental ones, and a good agreement was found. The linear dependence of the calculated EFG’s upon the anion parameter (u) proves the principal role of u for the determination of EFG at the B-site of spinel structure. /1/ P. Blaha, K. Schwarz, and J. Luitz, WIEN97, 1999 (ISBN 3-9501031-0-4). I. Burlakov is a A.v. Humboldt Fellow from the Institute of Applied Physics, Chisinau, Moldova.