  Electronic structure near Fermi level of Pr2CoFeO6 (at 300 K) was
investigated by X-ray photoemission spectroscopy (XPS) technique. All three
cations, i.e., Pr, Co and Fe were found to be trivalent in nature. XPS analysis
also suggested the system to be insulating in nature. Moreover, Raman
spectroscopy study indicated the random distribution of the B-site ions (Co/Fe)
triggered by same charge states. In temperature-dependent Raman study, the
relative heights of the two observed phonon modes exhibited anomalous behaviour
near magnetic transition temperature TN~270 K, thus indicating towards
interplay between spin and phonon in the system. Furthermore, clear anomalous
softening was observed below TN which confirmed the existence of strong
spin-phonon coupling occurring for at least two phonon modes of the system. The
line width analysis of the phonon modes essentially ruled out the role of
magnetostriction effect in the observed phonon anomaly. The investigation of
the lattice parameter variation across TN (obtained from the
temperature-dependent neutron diffraction measurements) further confirmed the
existence of the spin-phonon coupling.
