Spin–phonon coupling in epitaxial SrRuO ₃ heterostructures

Spin-phonon coupling is one of the fundamental interactions in functional materials, indispensable for understanding their unexpected magnetic ground states. Ferromagnetic SrRuO₃ 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 SrRuO₃ heterostructures. We deliberately decreased the exchange interactions within SrRuO₃ 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) SrRuO₃ 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 SrRuO₃, with accurate identification of the Raman modes. These results show that the phonon dynamics of SrRuO₃ is strongly influenced by the spin ordering, which can be efficiently tailored via atomically controlled epitaxial heterostructuring.