부산대학교 도서관

Analysis of the ESR spectra for powdered samples of (Ca,Na)-doped manganites is performed in the temperature range 220–320 K. It is shown that the samples under investigation are characterized by a broadened para-to ferromagnetic transition and complicated spectra within the transitional region. It is concluded that a satisfactory interpretation of the resonance data within the transitional region is possible only if the interference of coexisting phases is taken into account. Under these conditions, the resonance field for the paramagnetic phase is shown to increase with decreasing temperature, while that for the ferromagnetic phase first decreases and then approaches a value characteristic of the uniformly magnetized ferromagnetic sample. It is noted that the results obtained are in compliance with those predicted theoretically for spherical particles containing a mixture of the paramagnetic and ferromagnetic phases. [ABSTRACT FROM AUTHOR]