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HL: Halbleiterphysik

HL 27: Spinabh
ängiger Transport I

HL 27.2: Vortrag

Dienstag, 25. März 2003, 17:30–17:45, BEY/154

Investigation of ferromagnetic spinel semiconductors by hyperfine interactions of implanted nuclear probes — •Vyacheslav Samokhvalov¹, S. Unterricker¹, I. Burlakov¹, F. Schneider¹, M. Dietrich², and the ISOLDE Collaboration³ — ¹Institut für Angewandte Physik, TU Bergakademie Freiberg, D-09596 Freiberg/Sachsen — ²Technische Physik, Universität des Saarlandes, D-66041 Saarbrücken — ³CERN, CH-1211 Geneva 23, Switzerland

The ternary spinel-type compounds CdCr2Se4, CdCr2S4, HgCr2Se4 and CuCr2Se4 with Cr as transition metal form a special group of ferromagnetic semiconductors with Curie temperatures up to 430 K, which can have particular perspectives in spintronics because of the coexistence of semiconducting and ferromagnetic properties. We have investigated the hyperfine interaction of implanted nuclear probes in this group of magnetic semiconductors by PAC (perturbed angular correlations). In such compounds both magnetic hyperfine fields (Bhf) and electric field gradients (efg) allow a detailed study of the behavior of probes, which can additionally be essential doping atoms in these substances. Besides the popular 111In(111Cd) we used also 111mCd, 111Ag(111Cd), 77Br(77Se), 117Cd(117In), and 199mHg as PAC-probes by utilization of the unique possibilities at the ISOLDE on-line separator and implanter (CERN, Geneva, Switzerland). The main objective of these investigations was to examine the lattice site occupation and the behavior of the implanted probes. Moreover, the hyperfine fields can be used as test quantities for ab initio calculations of the electronic and spin structure.