Spin-phonon coupling in epitaxial SrRuO heterostructures.

Spin-phonon coupling is one of the fundamental interactions in functional materials, indispensable for understanding their unexpected magnetic ground states. Ferromagnetic SrRuO is a correlated metal with the potential for utilization in novel spintronic devices and serves as a promising platform for studying spin-phonon interactions. In this study, we used Raman spectroscopy to identify spin-phonon coupling in SrRuO heterostructures. We deliberately decreased the exchange interactions within SrRuO by reducing system dimensions, which was coherently observed in both temperature-dependent magnetization measurements and phonon spectra. To collect the Raman signals from the very thin (quasi-2D) SrRuO layers while maintaining the layer thickness, we fabricated epitaxial oxide superlattices with 50 repetitions of the layers. We also present polarization-dependent Raman spectra of SrRuO, with accurate identification of the Raman modes. These results show that the phonon dynamics of SrRuO is strongly influenced by the spin ordering, which can be efficiently tailored via atomically controlled epitaxial heterostructuring.