Wang Jianjin, Chen Jige
Department of Physics, Jiangxi Science & Technology Normal University, Nanchang 330013, China.
Zhangjiang Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China.
Phys Rev E. 2020 Apr;101(4-1):042207. doi: 10.1103/PhysRevE.101.042207.
Managing thermal transport in nanostructured materials possesses both theoretical and application value in thermoelectric and microelectronics design. Though a suppressed thermal conductivity could be easily achieved through disorder-induced phonon scattering in a superlattice, it is challenging to enhance thermal transport in a periodically designed lattice. In this paper, we show the possibility of mediating thermal conductivity from a suppressed to an enhanced value in a Fermi-Pasta-Ulam β superlattice with periodic cells of arithmetically increased nonlinearity. When the cell length is increased, thermal conductivity in the superlattice crosses over a suppressed region into an enhanced one and it is even higher than in a homogeneous lattice with the same nonlinearity strength. The mediation originates from the long-lived nonlinear wave packets as solitons across the disorder-induced interface between cells of the superlattice, while at the same time the normal vibrational modes as phonons are suppressed. Our result shows a promising strategy to manipulate thermal transport over a wide range in a superlattice with strong nonlinearity.
在纳米结构材料中控制热输运在热电和微电子设计中具有理论和应用价值。尽管通过超晶格中无序诱导的声子散射可以很容易地实现热导率的抑制，但在周期性设计的晶格中增强热输运具有挑战性。在本文中，我们展示了在具有算术增加非线性的周期性单元的费米-帕斯塔-乌拉姆β超晶格中，将热导率从抑制值调节到增强值的可能性。当单元长度增加时，超晶格中的热导率越过抑制区域进入增强区域，甚至高于具有相同非线性强度的均匀晶格中的热导率。这种调节源于作为孤子的长寿命非线性波包穿过超晶格单元之间由无序诱导的界面，同时作为声子的正常振动模式受到抑制。我们的结果展示了一种在具有强非线性的超晶格中广泛操纵热输运的有前景的策略。
