We report spatial localization of the effective magnetic field generated via the inverse Faraday effect employing surface plasmon polaritons (SPPs) at Au/garnet interface. Analyzing both numerically and analytically the electric field of the SPPs at this interface, we corroborate our study with a proof-of-concept experiment showing efficient SPP-driven excitation of coherent spin precession with 0.41 THz frequency. We argue that the subdiffractional confinement of the SPP electric field enables strong spatial localization of the SPP-mediated excitation of spin dynamics. We demonstrate two orders of magnitude enhancement of the excitation efficiency at the surface plasmon resonance within a 100 nm layer of a dielectric garnet. Our findings broaden the horizons of ultrafast spin-plasmonics and open pathways toward nonthermal opto-magnetic recording on the nanoscale.

中文翻译：

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介电介质中激光驱动的亚太赫兹自旋动力学的表面等离子介导的纳米级局域化

我们报告通过在Au /石榴石界面使用表面等离振子极化子（SPPs）的反法拉第效应产生的有效磁场的空间定位。在此界面上通过数值和分析方式分析了SPP的电场，我们用概念验证实验证实了我们的研究，该实验表明SPP驱动的励磁自旋进动具有0.41 THz频率的有效激发。我们认为，SPP电场的亚微分约束使SPP介导的自旋动力学激发具有较强的空间局限性。我们证明了在电介质石榴石的100 nm层内表面等离振子共振处的激发效率提高了两个数量级。