Giant negative magnetoresistance in GdI2: Prediction and realization

The electronic structure of the layered d(1) compound GdI2 has been examine d systematically in view of its relation to other layered d(1) systems incl uding superconducting and isostructural 2H-TaS2 and 2H-NbSe2. A van Hove ty pe instability is evident in suitable representations of the Fermi surface, The presence of the half-filled and magnetic 4f level should preclude the possibility of superconductivity. Instead GdI2 orders ferromagnetically at 290(5)K and displays large negative magnetoresistance approximate to 70% at 7 T close to room temperature, This finding provides support to the idea t hat materials can be searched rationally for interesting properties through high level electronic structure calculations. (C) 1999 Academic Press.