Effects on phase separation in the Raman-scattering and magnetization experiments of (La1−yNdy)2/3Ca1/3MnO3 (y=0.0, 0.5)

Abstract Raman-scattering and magnetization studies are presented for polycrystalline (La1−yNdy)1−xCaxMnO3 (y=0.0, 0.5, and x= 1 3 ) samples. The low-T Raman spectra for y=0.5 show two strong peaks at ≈480 and ≈620 cm−1 characteristic of the x=0 and x=0.5 (y=0.0) manganites. As T increases, the two modes broaden and decrease in spectral weight. The sample with y=0.0 also shows the two modes at all temperatures, though at low-T they are much less intense than those for y=0,5 sample. The low-field magnetization curve for y=0.5 shows a large thermal hysteresis and a broad ferromagnetic (FM) transition at T C ≈80 K (cooling) and T C ≈120 K (warming). In contrast, the sample with y=0.0 shows no thermal hysteresis and a sharp FM transition at T C =265 K . In contrast, the high-field ( H app =5 T ) curves are very similar for y=0.0 and y=0.5. The differences and similarities between both materials are discussed in terms of the coexistence of an AFM insulating and an FM metallic phase.