Spin-Phonon and Electron-Phonon Coupling in Pyrochlore Iridates (Y_1-x Pr _x )₂Ir₂O₇: An Investigation with Raman Spectroscopy

The complex interplay between the lattice geometry andspin-orbitcoupling in pyrochlore iridates is shown to give rise to many intriguingphenomena. Here, we report a temperature-dependent Raman scatteringstudy in a series of pyrochlore iridate materials (Y1-x Pr x )(2)Ir2O7 which shows magnetic and electronic transitionwith variation of both temperature as well as composition. Our Ramanstudies reveal an anomalous change in frequency and line width of F (2g ) and A (1g ) modes across its transition temperatureswhile the data in high temperatures mostly follow the anharmonic model.The variation of A (1g ) modeassociated with bending vibrations indicatesprominent spin-phonon coupling which is mostly induced by a Dzyaloshinskii-Moriyainteraction rather than exchange interaction. On the other hand, thesignature of electron-phonon interaction is also found to beprominent from stretching F (2g ) mode and opposite line width variation for sample with metallictransition. Thus, our study establishes prominent spin-phononand electron-phonon coupling and its connection with A-siteatoms in pyrochlore iridates.