1] Applied Science and Technology Graduate Group, University of California, Berkeley, California 94720, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [3] [4].
1] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA [3].
Nat Mater. 2014 Feb;13(2):168-72. doi: 10.1038/nmat3826. Epub 2013 Dec 8.
Elementary particles such as electrons or photons are frequent subjects of wave-nature-driven investigations, unlike collective excitations such as phonons. The demonstration of wave-particle crossover, in terms of macroscopic properties, is crucial to the understanding and application of the wave behaviour of matter. We present an unambiguous demonstration of the theoretically predicted crossover from diffuse (particle-like) to specular (wave-like) phonon scattering in epitaxial oxide superlattices, manifested by a minimum in lattice thermal conductivity as a function of interface density. We do so by synthesizing superlattices of electrically insulating perovskite oxides and systematically varying the interface density, with unit-cell precision, using two different epitaxial-growth techniques. These observations open up opportunities for studies on the wave nature of phonons, particularly phonon interference effects, using oxide superlattices as model systems, with extensive applications in thermoelectrics and thermal management.
与声子等集体激发不同，电子或光子等基本粒子是经常被用于波性质驱动研究的对象。从宏观性质上证明波粒交叉对于理解和应用物质的波动行为至关重要。我们在钙钛矿氧化物超晶格中明确地证明了理论上预测的从漫散射（粒子状）到镜面散射（波状）声子散射的交叉，这表现为晶格热导率随界面密度的减小而减小。我们通过合成电绝缘钙钛矿氧化物的超晶格，并使用两种不同的外延生长技术，以单元精度系统地改变界面密度来实现这一点。这些观察结果为使用氧化物超晶格作为模型系统研究声子的波动性质，特别是声子干涉效应，提供了机会，这在热电学和热管理中有广泛的应用。
