Zhang Shuai, Liu Yang, Sun Zhiyuan, Chen Xinzhong, Li Baichang, Moore S L, Liu Song, Wang Zhiying, Rossi S E, Jing Ran, Fonseca Jordan, Yang Birui, Shao Yinming, Huang Chun-Ying, Handa Taketo, Xiong Lin, Fu Matthew, Pan Tsai-Chun, Halbertal Dorri, Xu Xinyi, Zheng Wenjun, Schuck P J, Pasupathy A N, Dean C R, Zhu Xiaoyang, Cobden David H, Xu Xiaodong, Liu Mengkun, Fogler M M, Hone James C, Basov D N
Department of Physics, Columbia University, New York, NY, 10027, USA.
Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA.
Nat Commun. 2023 Oct 4;14(1):6200. doi: 10.1038/s41467-023-41773-x.
Ferroelectricity, a spontaneous and reversible electric polarization, is found in certain classes of van der Waals (vdW) materials. The discovery of ferroelectricity in twisted vdW layers provides new opportunities to engineer spatially dependent electric and optical properties associated with the configuration of moiré superlattice domains and the network of domain walls. Here, we employ near-field infrared nano-imaging and nano-photocurrent measurements to study ferroelectricity in minimally twisted WSe. The ferroelectric domains are visualized through the imaging of the plasmonic response in a graphene monolayer adjacent to the moiré WSe bilayers. Specifically, we find that the ferroelectric polarization in moiré domains is imprinted on the plasmonic response of the graphene. Complementary nano-photocurrent measurements demonstrate that the optoelectronic properties of graphene are also modulated by the proximal ferroelectric domains. Our approach represents an alternative strategy for studying moiré ferroelectricity at native length scales and opens promising prospects for (opto)electronic devices.
铁电性是一种自发且可逆的电极化现象，存在于某些类别的范德华（vdW）材料中。在扭曲的vdW层中发现铁电性为设计与莫尔超晶格畴结构和畴壁网络相关的空间依赖型电学和光学特性提供了新机遇。在此，我们采用近场红外纳米成像和纳米光电流测量来研究极小扭曲的WSe中的铁电性。通过对与莫尔WSe双层相邻的石墨烯单层中的等离子体响应进行成像，可视化了铁电畴。具体而言，我们发现莫尔畴中的铁电极化被印刻在石墨烯的等离子体响应上。互补的纳米光电流测量表明，石墨烯的光电特性也受到近端铁电畴的调制。我们的方法代表了一种在原生长度尺度上研究莫尔铁电性的替代策略，并为（光）电子器件开辟了广阔前景。
