Jin Chenhao, Tao Zui, Li Tingxin, Xu Yang, Tang Yanhao, Zhu Jiacheng, Liu Song, Watanabe Kenji, Taniguchi Takashi, Hone James C, Fu Liang, Shan Jie, Mak Kin Fai
Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.
School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
Nat Mater. 2021 Jul;20(7):940-944. doi: 10.1038/s41563-021-00959-8. Epub 2021 Mar 25.
Stripe phases, in which the rotational symmetry of charge density is spontaneously broken, occur in many strongly correlated systems with competing interactions. However, identifying and studying such stripe phases remains challenging. Here we uncover stripe phases in WSe/WS moiré superlattices by combining optical anisotropy and electronic compressibility measurements. We find strong electronic anisotropy over a large doping range peaked at 1/2 filling of the moiré superlattice. The 1/2 state is incompressible and assigned to an insulating stripe crystal phase. Wide-field imaging reveals domain configurations with a preferential alignment along the high-symmetry axes of the moiré superlattice. Away from 1/2 filling, we observe additional stripe crystals at commensurate filling 1/4, 2/5 and 3/5, and compressible electronic liquid crystal states at incommensurate fillings. Our results demonstrate that two-dimensional semiconductor moiré superlattices are a highly tunable platform from which to study the stripe phases and their interplay with other symmetry breaking ground states.
条纹相是指电荷密度的旋转对称性被自发打破的相，它出现在许多具有竞争相互作用的强关联系统中。然而，识别和研究这种条纹相仍然具有挑战性。在这里，我们通过结合光学各向异性和电子压缩性测量，在WSe/WS莫尔超晶格中发现了条纹相。我们发现在较大的掺杂范围内存在很强的电子各向异性，在莫尔超晶格填充率为1/2时达到峰值。1/2态是不可压缩的，并被归为绝缘条纹晶体相。宽场成像揭示了沿莫尔超晶格高对称轴具有优先取向的畴结构。在偏离1/2填充时，我们在填充率为1/4、2/5和3/5的 commensurate 填充处观察到额外的条纹晶体，在非 commensurate 填充处观察到可压缩的电子液晶态。我们的结果表明，二维半导体莫尔超晶格是一个高度可调谐的平台，可用于研究条纹相及其与其他对称性破缺基态的相互作用。
