Jeong Seung Gyo, Lim Soo Yeon, Kim Jiwoong, Park Sungkyun, Cheong Hyeonsik, Choi Woo Seok
Department of Physics, Sungkyunkwan University, Suwon 16419, Korea.
Nanoscale. 2020 Jul 14;12(26):13926-13932. doi: 10.1039/d0nr03282d. Epub 2020 Jul 1.
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.
自旋 - 声子耦合是功能材料中的基本相互作用之一，对于理解其意外的磁基态不可或缺。铁磁体SrRuO是一种相关金属，具有在新型自旋电子器件中应用的潜力，并且是研究自旋 - 声子相互作用的一个有前景的平台。在本研究中，我们使用拉曼光谱来识别SrRuO异质结构中的自旋 - 声子耦合。我们通过减小系统尺寸故意降低了SrRuO内的交换相互作用，这在温度依赖的磁化测量和声子光谱中都得到了一致的观察。为了在保持层厚度的同时从非常薄的（准二维）SrRuO层收集拉曼信号，我们制备了具有50层重复的外延氧化物超晶格。我们还展示了SrRuO的偏振相关拉曼光谱，并准确识别了拉曼模式。这些结果表明，SrRuO的声子动力学受到自旋有序的强烈影响，这可以通过原子控制的外延异质结构有效地进行调整。
