GIANT MAGNETORESISTANCE IN CR100-XFEX BULK GRANULAR ALLOYS

We report on the observation of giant magnetoresistance in magneticall y inhomogeneous bulk granular Cr100-xFex alloys. The largest magnetore sistance among the investigated alloys of 10.7 less than or equal to x less than or equal to 49.0 at. % amounts to 26% for x = 18.9 at. % at 5 K and 4 T. This is substantially larger than in other bulk random 3 d alloys and is of the same order of magnitude as that in granular fil ms. Concentration, temperature, and field dependences of the magnetore sistance are also similar to those observed in granular media. The ori gin of giant magnetoresistance in bulk Cr-Fe is attributed to the fiel d-induced alignment of Fe-rich ferromagnetic clusters in a Cr-rich mat rix. Giant magnetoresistance in Fe-Cr collapses just above x = 20 at. %, at which long-range ferromagnetic order sets in.