Emergence of spin-phonon coupling in Gd-doped Y2CoMnO6 double perovskite oxide: a combined experimental and ab-initio study

Abstract

We present Raman spectroscopy results backed by first-principles calculations and investi- gate the nature of possible spin-phonon coupling (SPC) in a Gd-doped Y2CoMnO6 (YGCMO) double perovskite oxide. The influence of Gd substitution, A-site ordering and anti-site dis- order is also studied. YGCMO exhibits anti-site disorder leading to both ferromagnetic (be- tween Co and Mn) and antiferromagnetic interactions (Co-Co, Mn-Mn, Gd-Co/Mn), making the SPC quite intriguing. An analysis of the temperature-dependent phonon frequencies for the stretching modes of YGCMO indicates that SPC here possibly emerges from the simul- taneous presence of competing ferromagnetic and antiferromagnetic interactions. The SPC strength comes out to be 0.29 cm−1. Our density functional theory (DFT) calculations show that Phonon modes shifted towards lower frequency with Gd doping. Similarly, A-site ordring and anti-site disorder significantly alter the Raman spectra. Experimental findings are also corroborated by first-principles DFT calculations, which indicate that anti-site disorder and Gd doping enhances SPC in YGCMO. This implies a strong influence of A-site cationic radii, and B-site (Co/Mn) ordering on SPC in the bulk double perovskite systems. The phonon dynamics of YGCMO are, therefore, correlated with magnetic ordering, indicating potential applications in spintronics devices.