Separation of Magnetic Phases in La_(1-x)Ca_xMnO_3 Manganites with 0.6≤x≤0.9

摘要

The magnetic properties of La_(1-x)Ca_xMnO_3 solid solutions were studied in wide temperature and magnetic field ranges, T = 2 - 600 K and H ≤ 50 kOe. Semiconducting compositions with 0.6 < x < 0.9 exhibited an unusual temperature behavior of magnetization and susceptibility with well-defined Curie and Neel temperatures. The simultaneous manifestation of both ferromagnetic and antiferromagnetic properties is evidence of the coexistence of two collinear magnetic phases. The content of impurity ions was shown to have a strong influence on the T_C and T_N values, whereas the ratio between the ferro- and antiferromagnetic phase volumes heavily depended on thermal treatment conditions. The magnetic properties of the whole series of La_(1-x)Ca_xMnO_3 soldi solutions can be explained in terms of the phase separation model.