by J. Fontcuberta.
Available online 30 August 2008.
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The semiconducting half-Heulser compound DyNiBi shows a negative giant magnetoresistance (GMR) below 200 K. 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 fields. The magnitude of the positive magnetoresistance changes slightly with the amount of impurity phase.
Keywords: A. Half-Heusler compounds; A. Semiconductors; C. Impurities in semiconductors; D. Giant magnetoresistance
PACS classification codes: 72.20.-i; 72.80.Ga; 81.40.Rs
Fig. 1. Resistivity and magnetoresistance of DyNiBi in different magnetic fields. The resistivity has been normalized to value of 300 K/ zero field.
Fig. 2. Field dependence or the resistivity at 80 K (top) and 10 K (bottom). The straight line is the fit according to Eq. (3). At 10 K two samples with slightly different bismuth impurities were measured (triangles=higher impurity contend).
Fig. 3. Scanning microscope image of a polished DyNiBi surface. Arrows mark Bi dots in the DyNiBi matrix (A) and on the surface (B) due to soft polishing.