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HL: Halbleiterphysik

HL 16: Störstellen/Grenz- und Oberfl
ächen I

HL 16.1: Vortrag

Dienstag, 28. März 2000, 09:30–09:45, H17

Hyperfine fields in the magnetic semiconductor CdCr2Se4 as investigated by PAC-spectroscopy — •Vyacheslav Samokhvalov¹, Igor Burlakov¹, Andreas Richter¹, Detlev Degering¹, Sepp Unterricker¹, Marc Dietrich², and Manfred Deicher² — ¹Institut für Angewandte Physik, TU Bergakademie Freiberg, D-09596 Freiberg/Sachsen — ²Fakultät für Physik, Universität Konstanz, D-78457 Konstanz

The radioactive probes 111mCd, 111Ag(111Cd), 111In(111Cd) and 77Br(77Se) were implanted in the spinel-type ferromagnetic semiconductor CdCr2Se4 at ISOLDE-CERN/Geneva on-line implanter and at Rossendorf cyclotron. By the nuclear method perturbed angular correlation (=PAC) electric field gradients and magnetic hyperfine fields were measured at different lattice sites. The hyperfine fields allow a clear decision of the probe positions in the spinel lattice. Measured hyperfine fields were compared with those calculated by the WIEN97-code /1/. According to our investigations Ag atoms are substituted at Cd-sites, whereas In is predominantly positioned at Cr-sites. But by thermal treatments with different conditions In-atoms can also occupy Cd-positions. Ag and In are very important doping atoms for p- and n-type conductivity CdCr2Se4, respectively.

/1/ P. Blaha, K. Schwarz and J. Luitz, WIEN97, 1999. ISBN 3-9501031-0-4