Study of Fe-doped La1−xCaxMnO3 (x≃1/3) using Mössbauer spectroscopy and neutron diffraction

Abstract

${\mathrm{La}}_{2/3}{\mathrm{Ca}}_{1/3}{\mathrm{MnO}}_3$ doped with Fe were studied by Mössbauer spectroscopy and neutron powder diffraction. The Mössbauer spectra (MS) reveal that Fe substitutes for Mn as ${\mathrm{Fe}}^{3+}$ $\mathrm{}(S=5/2\mathrm{})\mathrm{}$ and is antiferromagnetically coupled to the Mn host lattice. The magnetic behavior, from the neutron diffraction data, is that of a typical 3D Heisenberg ferromagnet. The temperature evolution of the MS differs from that of the neutron data, especially above 40 K. The data can be interpreted using a model based on an antiferromagnetic impurity in a ferromagnetic host. In such a system, the ground state is inhomogeneous resulting in spin states with reduced spin and the spin excitations are localized in the immediate neighborhood of the impurity atoms. Finally, at $T\approx {0.9T}_c$ the MS indicate the onset of charge localization.