Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 11: Spindependent Transportphenomena II

MA 11.8: Talk

Monday, February 25, 2008, 17:00–17:15, H 0112

Giant magnetoresistance and extraordinary magnetoresistance in inhomogeneous semiconducting RENiBi compounds — •Frederick Casper and Claudia Felser — Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg - University, 55099 Mainz

Some inhomogeneous semiconducting C1_b compounds RENiBi (RE = Gd, Dy, Er) show a negative giant magnetoresistance (GMR) above the magnetic ordering temperature in the paramagnetic temperature regime. Except for a weak deviation, this magnetoresistance scales roughly with the square of the magnetization in the paramagnetic state, and is related to the metal-insulator transition. At low temperature, a positive magnetoresistance is found, which can be suppressed by high magnetic fields. The nonmagnetic inhomogeneous semiconducting compound LuNiBi shows a large postitve MR ratio of 25% at room temperature. The positive MR may be due to metallic bismuth impurities in the sample that cause an extraordinary magnetoresistance (EMR).

This work was supported by DFG grant FE633/1-1 within SPP1166