LaMn0.5Co0.5O3 (LMCO) is a ferromagnetic perovskite with monoclinic structure having distinct physical properties. The ferromagnetic ordering temperatures (Tc) for the two different phases are 138 K and 243 K. Such contrasting characteristics have been assigned to the lattice effects. Using Raman spectroscopy we find that the stretching mode (ωs) deviates from the regular dependence of ωanh(T) = ωoC(1+(2/e(hωo/2kBT)−1)) for T<Tc. While FWHM is expected to decrease when the temperature decreases, we observe an anomalous behaviour. This deviation from the expected behaviour suggests the increase in phonon lifetime, which is consistent with the decrease in phonon energy. This is clearly due to strong spin‐phonon coupling near the Tc for both the phases of LMCO. Smaller FWHM of ωs(T) for the high Tc phase indicates higher phonon life time and higher B‐site ordering when compared to the low Tc sample.

While the low Tc phase follows ES‐VRH transport mechanism, in case of the high Tc phase we are unable to fit any of the known conduction mechanisms such as VRH, polaron hopping etc. From Raman scattering we find that the bending mode has a continuous change in the paramagnetic region. The bending mode being temperature dependent might prevent the transport to follow any known conduction mechanism in case of the high Tc phase.

This content is only available via PDF.
You do not currently have access to this content.