Magnetization jumps and thermal cycling effect induced by impurities in Pr0.6Ca0.4MnO3

Staircase-like magnetic-field-driven magnetization curves (M(H)) from an antiferromagnetic to a ferromagnetic state have been obtained in Pr0.6Ca0.4MnO3 substituted at the Mn site. Although both non magnetic (Ga3+, 3d(10)) and magnetic (Cr3+, 3d(3)) substituted cations are able to induce an insulator-to-metal transition, a very distinct magnetic behaviour is observed as the impurity content increases. In the case of Ga3+, the induced ferromagnetic fraction goes through an optimum (similar to40%) for 3% Ga whereas, with only 2% of Cr3+, this fraction reaches 95%. Interestingly, as the ferromagnetic fraction is not too high (less than or equal to50%), staircase-like M(H) curves are observed at low temperature. The number of magnetization jumps necessary to reach a complete ferromagnetic state is smaller than that of the Mn-site substituted Pr0.5Ca0.5MnO3. Moreover, in the case of Ga3+, there exists a clear relationship between the thermal cycling effect and the reproducibility of the M jumps. These results are discussed in the framework of a martensitic-like transition.