报告题目 (Title)：Nonlinear Energy Carriers in Low-dimensional Crystalline Solids: Shockwaves and Solitons（低维晶体材料中的非线性载流子：激波与孤子）

报告人 (Speaker)： 陈济舸 副研究员 (中国科学院上海高等研究院)

报告时间 (Time)：2022年11月14日(周一) 10：00-12：00

报告地点 (Place)：腾讯会议 940-737-046

邀请人(Inviter)：郭盼

主办部门：理学院物理系

报告摘要：

It was long believed that, as pointed out by Peierls, even close to the melting point the excitations in ordinary three-dimensional crystalline solids are so small that the nonlinear waves like solitons can be neglected. As a result, a thorough and satisfactory understanding of energy transport beyond the low-temperature region in solid crystalline materials is still missing. We disagree with this idea and suggest a crossover of wave-packet dynamic from phonon- to nonlinear wave-dominated (shock wave or soliton dominated) state in some two-dimensional materials at high temperatures far below its melting point in some low-dimensional materials. Excitation of nonlinear energy carriers, i.e., shock waves and solitons, determines the scaling relations in the anomalous thermal conduction process. The crossover relates to a second-order phase transition where the superposition symmetry of linear waves (phonons) is broken due to the enhanced nonlinearity at high temperatures. We further suggest a mediation strategy to manipulate thermal conductivity through long-lived solitons over a wide range in low-dimensional nonlinear crystalline solids.