堆垛层错促成中心对称范德华 RhI3 中的二次谐波产生
Stacking faults enabled second harmonic generation in centrosymmetric van der Waals RhI3
AI总结：
该研究以中心对称范德华RhI3为例，结合理论、表征与静水压实验，揭示AC-C堆垛层错诱导并调控SHG的机制，实现最高6.9倍增强。
摘要：
范德华（vdWs）材料中的二次谐波产生（SHG）因其在集成非线性光学和光电子应用方面的潜力而受到广泛关注。vdWs材料中的堆垛层错是一种典型的平面缺陷，可引入新的自由度来调控晶体对称性及由此产生的SHG响应；然而，vdWs材料中由堆垛层错主导的SHG的物理起源和可调性仍不清楚。本文以本征中心对称的vdWs RhI3为例，从理论上揭示了由堆垛层错主导的SHG响应的起源：该SHG响应来自能量上有利的AC-C堆垛层错，其中在810 nm波长下，布里渊区中沿高对称路径Γ-M和Γ-K的电子跃迁起主导作用。这种由堆垛层错主导的SHG响应进一步通过结构表征和SHG测量得到证实。此外，通过对RhI3施加静水压，揭示了结构演化与SHG响应之间的关联，SHG增强最高可达6.9倍；在压缩下更强的层间相互作用导致电子跃迁能降低、动量矩阵元更大，从而放大了SHG极化率。本研究为基于策略性设计的堆垛层错、开拓非线性纳米光学新途径奠定了有前景的基础。
英文摘要：
Second harmonic generation (SHG) in van der Waals (vdWs) materials has garnered significant attention due to its potential for integrated nonlinear optical and optoelectronic applications. Stacking faults in vdWs materials, a typical kind of planar defect, can introduce a new degree of freedom to modulate the crystal symmetry and resultant SHG response, however, the physical origin and tunability of stacking-fault-governed SHG in vdWs materials remain unclear. Here, taking the intrinsically centrosymmetric vdWs RhI3 as an example, we theoretically reveal the origin of stacking-fault-governed SHG response, where the SHG response comes from the energetically favorable AC- Cstacking fault of which the electrical transitions along the high symmetry paths Gamma-M and Gamma-K in the Brillion zone play the dominant role at 810 nm. Such stacking-fault-governed SHG response is further confirmed via structural characterizations and SHG measurements. Furthermore, by applying hydrostatic pressure on RhI3, the correlation between structural evolution and SHG response is revealed with SHG enhancement up to 6.9 times, where the decreased electronic transition energies and huger momentum matrix elements due to the stronger interlayer interactions upon compression magnify the SHG susceptibility. This study develops a promising foundation based on strategically designed stacking faults for pioneering new avenues in nonlinear nano-optics.
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