Dynamic Optical Tuning of Interlayer Interactions in the Transition Metal Dichalcogenides

作者：Mannebach Ehren M; Nyby Clara; Ernst Friederike; Zhou Yao; Tolsma John; Li Yao; Sher Meng Ju; Tung I Chen; Zhou Hua; Zhang Qi; Seyler Kyle L; Clark Genevieve; Lin Yu; Zhu Diling; Glownia James M; Kozina Michael E; Song Sanghoon; Nelson Silke; Mehta Apurva; Yu Yifei; Pant Anupum; Aslan Ozgur Burak; Raja Archana; Guo Yinsheng; DiChiara Anthony; Mao Wendy; Cao Linyou; Tongay Sefaattin; Sun Jifeng; Singh David J; Heinz Tony F; Xu Xiaodong; MacDonald Allan H; Reed Evan; Wen Haidan

来源：Nano Letters, 2017, 17(12): 7761-7766.

DOI：10.1021/acs.nanolett.7b03955

• 2D materials
• interlayer van der Waals interactions
• ultrafast
• Casimir effect
• femtosecond X-ray scattering

Modulation of weak interlayer interactions between quasi-two dimensional atomic planes in the transition metal dichalcogenides (TMDCs) provides avenues for tuning their functional properties. Here we show that above gap optical excitation in the TMDCs leads to an unexpected large-amplitude, ultrafast compressive force between the two-dimensional layers, as probed by in situ measurements of the atomic layer spacing at femtosecond time resolution. We show that this compressive response arises from a dynamic modulation of the interlayer van der Waals interaction and that this represents the dominant light induced stress at low excitation densities. A simple analytic model predicts the magnitude and carrier density dependence of the measured strains. This work establishes a new method for dynamic, nonequilibrium tuning of correlation-driven dispersive interactions and of the optomechanical functionality of TMDC quasi-two-dimensional materials.

• 出版日期2017-12