Electrical properties of Co-doped beta-FeSi2 crystals

beta -FeSi2 crystals were grown from high-purity starting materials by chem ical vapor transport. The crystals were in situ n-type doped adding Co to t he source material. Electrical properties have been investigated by tempera ture-dependent resistivity and Hall effect measurements. Above 100 K, we ob served conventional conduction band transport. The Co doping was found to c reate a shallow donor level at E-c-0.053 eV. Hall mobilities up to 50 cm(2) /Vs were observed. At lower temperatures defect band conduction dominates t he electrical transport and negative magnetoresistance is observed. The mai n contribution to the Hall voltage observed at low temperatures arises from the anomalous Hall effect. (C) 2001 American Institute of Physics.