11/20(목) 전문가초청특강은 POSTECH 오명철 교수님을 모시고 진행합니다.

관심있는 분들의 많은 참석 부탁드립니다.

ㅁ주제: Fabrication and nanoscale characterization of Twisted van der Waals heterostructures 

ㅁ일시: 11/20(목) 16:00

ㅁ장소: 제2종합연구동 83188호

ㅁ약력: 

ㅁ초록:

Recent advances in the fabrication of two-dimensional van der Waals (vdW) heterostructure devices have enabled precise control over the rotational angle mismatch between the atomic lattices of two vertically stacked layers, thereby modifying the electronic structure of the parent materials [1,2]. By tuning the carrier density in these twisted vdW heterostructures, the material exhibits a rich spectrum of emergent quantum phenomena, such as correlated insulators, unconventional superconductivity, and non-trivial topological phases [1–4].

In this talk, I will present our approach for the precise fabrication of twist-angle–controlled vdW graphene heterostructure devices designed for surface condition sensitive measurements, such as scanning probe microscopy and angle-resolved photoemission spectroscopy (ARPES). Furthermore, I will discuss recent advances in scanning tunneling microscope (STM) characterization techniques used to probe their electronic landscapes, highlighting our STM studies on the electronic properties of both correlated and topological phases in these heterostructure devices [3,4], including our recent observations of the Hofstadter-butterfly fractal spectrum in large-scale moiré superlattice structures of twisted graphene heterostructures [5]. These findings not only provide critical insights into the fundamental physics of twisted vdW materials but also underscore the potential of twisted graphene heterostructures as a versatile platform for future quantum device applications.

[1] Y. Cao et al., Nature 556, 43–50 (2018)

[2] J. Cai*, E. Anderson* et al., Nature 622, 63-68 (2023)

[3] D. Wong*, K.P. Nuckolls*, M. Oh*, B. Lian* et al., Nature 582, 198–202 (2020)

[4] M. Oh*, K.P. Nuckolls*, D. Wong* et al., Nature 600, 240–245 (2021)

[5] K. P. Nuckolls*, M. G. Scheer*, D. Wong*, M. Oh* et al. Nature 639, 60–66 (2025)

*Equally contributed