Griffiths phase-like behavior and origin of spin-phonon interaction in Eu0.75Y0.25MnO3

The magnetic state and the spin-phonon coupling in the Eu0.75Y0.25MnO3 are investigated using temperature dependent magnetization, Raman spectroscopy and Mossbauer spectroscopy measurements. The magnetization data showed bifurcation in zero-field cooled and field-cooled warming curves and indicate two antiferromagnetic transitions at 47 K and 22 K. Short range ferromagnetic correlations are clearly observed well above the antiferromagnetic transition temperatures, which are attributed to the presence of Griffiths-like phase. The temperature dependent Raman spectroscopy measurements showed anomalous softening of phonon modes well above the antiferromagnetic ordering temperature of similar to 47 K and also showed signatures of both the ordering temperatures. The Mossbauer spectra showed anomalous changes in hyperfine field as a function of temperature which match with the temperature at which B-2g phonons showed softening.