روزنامه با شماره پیاپی سال 2002

4

353

356

We report on the magnetization, resistivity and magnetoresistance measurements on polycrystalline samples of Sm0.55Sr0.45−xCexMnO3 (x=0 and 0.05). Substitution of Ce(x=0.05) reduced the para–ferromagnetic transition from ∼140 K (x=0) to ∼90 K. For x=0, the colossal magnetoresistance (CMR) (−100(ρB−ρ0)/ρ0) effect of 55% (143 K) was observed in a field of 0.6 Oe. On the other hand, for the x=0.05 sample, at 93 K, the CMR effect which was 32% in the field of 65 Oe increased to 87% in the field of 0.6 T. Our data rule out grain boundary effects as the principal cause but point out the applicability of the phase separation model.

Acta Tropica

2002

Acta Tropica