Orientational Switching of Perpendicular Magnetic Anisotropy and Near-Infrared Plasmonic States in SrRuO₃ Thin Films: Implications for Spintronic Devices

The precise manipulation of perpendicular magnetic anisotropy (PMA) and near-infrared plasmonic states holds immense significance for advanced nanoscale spintronics devices including magnetic random-access memory and epsilon-near-zero (ENZ) photonic devices. Notwithstanding the inherent tendency of oxide thin films to favor an in-plane magnetic easy axis, our study unveils an innovative approach to exert experimental control over magnetic anisotropy, magnetic phase in SrRuO3 (SRO) films by growing them coherently and controlling at nanoscale levels via reflection high-energy electron diffraction (RHEED)-assisted pulsed laser deposition (PLD) on distinctively oriented─specifically, (001), (011), and (111) SrTiO3 (STO) single crystalline substrates. Our comprehensive magnetic measurements unequivocally confirm a clear dependence on magnetic anisotropy with more than one competing magnetic phase with different coercivity and saturation magnetization. A larger perpendicular magnetic anisotropy (PMA) is observed for coherently strained SRO films on (001)-oriented STO compared to their counterparts on (011) and (111)-oriented STO. On the other hand, the orientation-dependent SRO films exhibit tunable plasmonic ENZ, increased metallicity, flexible optical conductivity, and customizable optical transparency in the near-infrared region. These results not only provide a straightforward and effective pathway for achieving tunable PMA and transparent plasmonic states in epitaxial oxide layers but also hold the potential to develop state-of-the-art oxide-based optospin–orbit coupled spintronic switching and memory devices.