EPR study of Pr0.7Sr0.3−xBaxMnO₃ lanthanum manganites

This is the authors' abstract. We don't add key points for this paper.

Among the wide variety of colossal magnetoresistance materials the Pr‐compositions occupy some special places. Namely, in zero magnetic field the Pr 1− y Ca y MnO 3 samples are insulators for any level of Ca doping and show low field hysteresis. Pr 0.7 Ba 0.3 MnO 3 composition is also insulating at low as well as at high temperatures. The combined Pr‐ and (Sr, Ba)‐doped perovskite‐like manganites should show interesting properties due to the large difference between the Pr and Sr, Ba ionic size. In this work we present an electron paramagnetic resonance (EPR) study of Pr 0.7 Sr 0.3− x Ba x MnO 3 perovskite ( x = 0.00, 0.15 and 0.30). We observed that the intensity of the EPR line decreases exponentially with temperature. The activation energy values derived from the temperature dependencies of EPR line intensity equals 0.16 eV, 0.09 eV and 0.08 eV for the x = 0.00, 0.15 and 0.30 compositions, respectively. The temperature dependence of the EPR linewidth showed a minimum near the T C . The temperature and concentration dependencies of EPR linewidth and line intensity will be discussed. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)