Local Structure and Dynamic Properties of Mn Substituted Manganites Studied by EXAFS and Anelastic Spectroscopy

We present extended X-ray absorption fine structure (EXAFS) and anelastic spectroscopy measurements performed on (La0.63Ca0.37)(Mn1-yMy)O3 manganites (M = Cr or Ni and y = 0.03, 0.08). The ferromagnetic metallic phase maintains its long-range character even after Mn substitution with non- Jahn-Teller ions, but both the doping species (Ni or Cr) lower the Curie temperature and broaden the magnetic transition. EXAFS suggests the presence of distorted insulating zones in the framework of phase inhomogeneity. Moreover, a strong dependence of the real part of the complex dynamic Young’s modulus and of the elastic energy-loss coefficient on the Mn substitution is evidenced by the anelastic spectroscopy spectra. These results confirm the correlation among local lattice disorder, dynamic and magnetic degrees of freedom and also evidence the possibility to tune manganites physical properties acting on their chemical composition.