Role of Laser Excitation Wavelength and Power in the Fano Resonance Scattering in RFe0.50Cr0.50O3(R = Sm, Er, and Eu): A Brief Raman Study

Abstract

Here in the present report, we have extensively studied the impact of the excitation laser wavelength and laser power on the Raman spectrum of mixed Fe-Cr-based rare-earth perovskites. Resonant and excitation laser power experiments carried out for these samples suggest the orbital-mediated lattice rearrangement because of electronic excitation from Cr3+(d3)-O2--Fe3+(d5) ions, which results in an antiresonance dip around 600 cm-1. The presence of an antiresonance dip even at low laser power is ascribed to Fano interference between the electronic continuum and phonons. Furthermore, with increasing the laser power, the Raman modes show a systematic red shift and asymmetrically broadened Raman lines, which is understood in terms of laser-induced heating effects. Consequently, it also upraises a question about the intrinsic nature of Fano resonance observed for a sample, because it may have laser-induced origin too. Therefore, the present study provides an important outcome emphasizing the high sensitivity of Raman measurements, wherein the laser power of the incident photons plays a major role such that it can even perturb the original features of samples. © 2022 American Chemical Society. All rights reserved.