The effect of magnetic ordering on the giant magnetoresistance of Cr-Fe-V and Cr-Fe-Mn

Cr-rich Cr1-xFex alloys with compositions in the vicinity of mixed ferromag netic and antiferromagnetic exchange (x = 0.18) exhibit giant magnetoresist ance. In order to understand the influence of the antiferromagnetism of Cr on the giant magnetoresistance one can manipulate the antiferromagnetic exc hange either by adding vanadium, which destroys the antiferromagnetism of C r, or by adding manganese, which enhances it. Cr-Fe-V and Cr-Fe-Mn alloys a lso have Curie temperatures that lie between low temperatures and room temp erature in the concentration region where giant magnetoresistance is observ ed. Therefore, they are also used as samples to study the magnetoresistance as a function of the strength of FM exchange. We discuss these points in t he light of temperature and concentration-dependent magnetoresistance exper iments on Cr0.99-xFexV0.01, Cr0.96-xFexV0.04. Cr0.90-xFexMn0.10 and Cr0.55F exMn0.45-x alloys. Results indicate that the most favorable condition for a large magnetoresistance in these alloys occurs at temperatures near the Cu rie temperature. (C) 2000 Published by Elsevier Science B.V. All rights res erved.