NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore.
Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore.
Nat Commun. 2017 May 12;8:15271. doi: 10.1038/ncomms15271.
Plasmonics has attracted tremendous interests for its ability to confine light into subwavelength dimensions, creating novel devices with unprecedented functionalities. New plasmonic materials are actively being searched, especially those with tunable plasmons and low loss in the visible-ultraviolet range. Such plasmons commonly occur in metals, but many metals have high plasmonic loss in the optical range, a main issue in current plasmonic research. Here, we discover an anomalous form of tunable correlated plasmons in a Mott-like insulating oxide from the SrNbO family. These correlated plasmons have multiple plasmon frequencies and low loss in the visible-ultraviolet range. Supported by theoretical calculations, these plasmons arise from the nanometre-spaced confinement of extra oxygen planes that enhances the unscreened Coulomb interactions among charges. The correlated plasmons are tunable: they diminish as extra oxygen plane density or film thickness decreases. Our results open a path for plasmonics research in previously untapped insulating and strongly-correlated materials.
等离子体学因其将光限制在亚波长尺寸的能力而引起了极大的关注，从而创造出具有前所未有的功能的新型设备。人们正在积极寻找新的等离子体材料，特别是那些在可见-紫外范围内可调谐等离子体和低损耗的材料。这种等离子体通常存在于金属中，但许多金属在光学范围内具有较高的等离子体损耗，这是当前等离子体研究中的一个主要问题。在这里，我们在 SrNbO 族的类莫特绝缘氧化物中发现了一种可调谐相关等离子体的异常形式。这些相关等离子体在可见-紫外范围内具有多个等离子体频率和低损耗。理论计算支持，这些等离子体源于纳米级间距的额外氧平面的限制，增强了电荷之间的未屏蔽库仑相互作用。相关等离子体是可调谐的：随着额外氧平面密度或薄膜厚度的降低而减小。我们的结果为在以前未开发的绝缘和强相关材料中的等离子体学研究开辟了道路。
