Department of Physics, University of California, San Diego (UCSD), La Jolla, CA 92093, USA.
Science. 2014 Mar 7;343(6175):1125-9. doi: 10.1126/science.1246833.
van der Waals heterostructures assembled from atomically thin crystalline layers of diverse two-dimensional solids are emerging as a new paradigm in the physics of materials. We used infrared nanoimaging to study the properties of surface phonon polaritons in a representative van der Waals crystal, hexagonal boron nitride. We launched, detected, and imaged the polaritonic waves in real space and altered their wavelength by varying the number of crystal layers in our specimens. The measured dispersion of polaritonic waves was shown to be governed by the crystal thickness according to a scaling law that persists down to a few atomic layers. Our results are likely to hold true in other polar van der Waals crystals and may lead to new functionalities.
由不同二维固体的原子层薄晶体组装而成的范德华异质结构正在成为材料物理的一个新范例。我们使用红外纳米成像研究了代表性的范德华晶体六方氮化硼中表面声子极化激元的性质。我们在实空间中激发、探测和成像极化激元波，并通过改变样品中的晶体层数来改变它们的波长。根据一个扩展定律，我们的实验表明极化激元波的色散受晶体厚度的控制，该定律一直持续到几个原子层。我们的结果可能适用于其他极性范德华晶体，并可能带来新的功能。
