Park Joon Young, Shin Young Jae, Shin Jeacheol, Kim Jehyun, Jo Janghyun, Yoo Hyobin, Haei Danial, Hyun Chohee, Yun Jiyoung, Huber Robert M, Gupta Arijit, Watanabe Kenji, Taniguchi Takashi, Park Wan Kyu, Shin Hyeon Suk, Kim Miyoung, Kim Dohun, Yi Gyu-Chul, Kim Philip
Department of Physics, Harvard University, Cambridge, MA, USA.
Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul, Republic of Korea.
Nat Mater. 2025 Mar;24(3):399-405. doi: 10.1038/s41563-024-02079-5. Epub 2025 Jan 22.
Atomically thin van der Waals (vdW) films provide a material platform for the epitaxial growth of quantum heterostructures. However, unlike the remote epitaxial growth of three-dimensional bulk crystals, the growth of two-dimensional material heterostructures across atomic layers has been limited due to the weak vdW interaction. Here we report the double-sided epitaxy of vdW layered materials through atomic membranes. We grow vdW topological insulators SbTe and BiSe by molecular-beam epitaxy on both surfaces of atomically thin graphene or hexagonal boron nitride, which serve as suspended two-dimensional vdW substrate layers. Both homo- and hetero-double-sided vdW topological insulator tunnel junctions are fabricated, with the atomically thin hexagonal boron nitride acting as a crystal-momentum-conserving tunnelling barrier with abrupt and epitaxial interfaces. By performing field-angle-dependent magneto-tunnelling spectroscopy on these devices, we reveal the energy-momentum-spin resonance of massless Dirac electrons tunnelling between helical Landau levels developed in the topological surface states at the interfaces.
原子级薄的范德华（vdW）薄膜为量子异质结构的外延生长提供了一个材料平台。然而，与三维体晶体的远程外延生长不同，由于范德华相互作用较弱，二维材料异质结构跨原子层的生长受到了限制。在此，我们报告了通过原子膜实现范德华层状材料的双面外延。我们通过分子束外延在原子级薄的石墨烯或六方氮化硼的两个表面上生长范德华拓扑绝缘体SbTe和BiSe，它们作为悬浮的二维范德华衬底层。制备了同型和异型双面范德华拓扑绝缘体隧道结，原子级薄的六方氮化硼作为具有陡峭外延界面的晶体动量守恒隧道势垒。通过对这些器件进行场角相关的磁隧道光谱测量，我们揭示了在界面处拓扑表面态中形成的螺旋朗道能级之间无质量狄拉克电子隧穿的能量 - 动量 - 自旋共振。
