Magnetoresistance in spinel-type MgxCu1-xCr2S4

CuCr2S4 shows a p-type metallic conductivity and ferromagnetism with Curie temperatures T-c of 375 K, and exhibit magnetic anomaly at 84 K (= T-m). CuCr2S4 exhibits the coexistence of both the ferromagnetism and spin-glass with the irreversible magnetic effect below T-m. The partial 20% Mg-substitution for Cu in CuCr2S4 slightly reduces the T-c and T-m. Magnetorsi stance of MgxCu1-xCr2S4 can be expressed as Deltap = aH(2) - bH(n) below T-m. a, b, and it are temperature-dependent adjustable parameters. These unique MR behavior would be attributed to the coexistence of the ferromagnetism and spin-glasslike order below T-m. Mg-substitution decreased the conducting carrier, which forms the conduction band whose orbital motion gave the positive MR contribution. Therefore, Mg-substitution gave smaller positive MR contribution and consequently gave larger negative MR (maximum 7% at 10 K) in Mg0.2Cu0.8Cr2S4. These results suggest that Cr 3d band filling control can be expected to give functional magnetoelectric transport properties in CuCr2S4. (C) 2004 Elsevier Ltd. All rights reserved.