Intergranular tunneling magnetoresistance of mechanically alloyed (Cr-M)O2 powder compacts

The (Cr-M)O₂ (M=V, Mn, Fe, Co) powders were synthesized by the mechanochemical method and the magnetoresistance (MR) effect of their powder compacts was investigated as a function of the type and content of the dopant. The findings are summarized as follows. 1) Substituting limit of M for Cr in CrO₂ was 30 at% for V, Mn, and Co, and 5 at% for Fe. 2) Doping with V effectively decreases the T_C, while Fe significantly elevates the same (420 K with 5 at% Fe). Furthermore, the changes observed in the cases of Co and Mn was marginal. 3) MR ratio was significantly enhanced with the doping of 5 at% of Fe, however, decreased in the cases of V and Co doping. 4) The reason for the MR enhancement in (Cr-Fe)O₂ powder compacts is due to the change in the barrier characteristics.