Interactions between light and magnetic matter attracted great attention lately due to their potential applications in nanophotonics, spintronics, and high-accuracy sensing. Here, we grew bismuth quantum dots (Bi–QDs) with strong spin–orbit coupling on a magnetic insulator yttrium iron garnet (YIG) via molecular beam epitaxy. The YIG/Bi–QDs material shows an enhanced magneto-optical Kerr rotation up to 130% compared with that of a bare YIG film. The Bi–QDs were also introduced onto a lutetium–bismuth co-doped YIG film to form a hybrid system with remarkably enhanced Kerr rotation (from 1626 to 2341 mdeg). Ferromagnetic resonance measurements showed an increased effective magnetization as well as interfacial spin–orbit field in the YIG/Bi–QD heterostructures. Localized plasmons were mapped using electron energy loss spectroscopy with high spatial resolution, revealing enhanced plasmon intensity at both the Bi–QD surface and YIG/Bi–QD interface. Introducing Bi-QDs onto the YIG film enhanced Kerr rotation owing to the attenuated optical reflection and increased effective magnetization. The Bi–QD-enhanced magneto-optical effect enables development of efficient nanoscale light switching, spintronics, and even plasmonic nano-antennas.

由于光和磁物质之间的相互作用在纳米光子学，自旋电子学和高精度传感中的潜在应用，近来引起了极大的关注。在这里，我们通过分子束外延在磁绝缘子钇铁石榴石（YIG）上生长了具有强自旋轨道耦合的铋量子点（Bi-QDs）。与裸YIG膜相比，YIG / Bi-QDs材料显示出的磁光Kerr旋转增强了130％。Bi-QDs还被引入到-铋共掺杂的YIG膜上，形成了具有明显增强的Kerr旋转（1626至2341 mdeg）的混合系统。铁磁共振测量结果表明，YIG / Bi-QD异质结构中有效磁化强度以及界面自旋轨道场增大。使用具有高空间分辨率的电子能量损失谱对局部等离激元进行了映射，揭示了在Bi–QD表面和YIG / Bi–QD界面处均具有增强的等离激元强度。将Bi-QD引入YIG薄膜可增强Kerr旋转，这是由于衰减了的光反射和增加了有效磁化强度。借助Bi-QD增强的磁光效应，可以开发出高效的纳米级光开关，自旋电子器件，甚至是等离子体纳米天线。