Probing the multi spin-phonon coupling and local B-site disorder in Pr2CoFeO6 by Raman spectroscopy and correlation with its electronic structure by X-ray photoemission spectroscopy

TL;DR

This study combines Raman spectroscopy, X-ray photoemission, and neutron diffraction to reveal strong spin-phonon coupling and B-site disorder in Pr2CoFeO6, linking electronic structure, lattice dynamics, and magnetic transition behavior.

Contribution

It provides new insights into the multi spin-phonon interactions and B-site disorder in Pr2CoFeO6 using combined spectroscopic and diffraction techniques.

Findings

Strong spin-phonon coupling observed below TN

B-site disorder confirmed by Raman and neutron diffraction

Electronic structure indicates insulating behavior

Abstract

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.