Phase separation in La0.67Ca0.33Mn0.9Fe0.1O3: a Moessbauer study

Moessbauer spectroscopy of La0.67Ca0.33Mn0.9Fe0.1O3 shows phase separation above and below the magnetic transition temperature TC. These phase separations are found to be independent and related to different phenomena. The relative volumes of the two phases above and below TC are also very different. Moessbauer spectra above TC show that the phase splitting is due to different lattice distortions around Fe in the two phases. The paramagnetic component showing large distortion disappears when the magnetic hyperfine splitting appears on lowering the temperature. The phase splitting below TC is due to a difference in the nature of magnetic ordering and the degree of covalence of the magnetic ions in the two phases. DC magnetization shows that the spin ordering in the two phases is collinear and non-collinear, respectively. At low temperatures, the non-collinear phase converts into the collinear phase when the applied magnetic field exceeds a certain value. When the field is withdrawn, the non-collinear phase is not fully regained