Real-space study of monolayer hBN encapsulated bilayer MoTe2 devices

Abstract Molybdenum ditelluride (MoTe 2 ) has recently emerged as a quantum material platform, especially exhibiting the fractional quantum anomalous Hall (FQAH) effect and unconventional superconductivity in its twisted bilayer configuration. However, a deep understanding of the strong many-body correlations and superconductivity in this system requires systematic real-space studies of the electronic and structural properties of few-layer MoTe 2 by scanning tunneling microscopy (STM). This remains challenging due to the high air-sensitivity of MoTe 2 and the difficulties associated with STM device fabrication. Here, we adopted an encapsulation strategy employing monolayer hexagonal boron nitride (hBN) that enabled atomic-scale characterization of air-sensitive MoTe 2 devices via scanning probe techniques. This approach allowed us to probe both natural and twisted bilayer MoTe 2 (tMoTe 2 ) (with twist angle $\theta = 2.35^{\circ}$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>θ</mml:mi> <mml:mo>=</mml:mo> <mml:msup> <mml:mn>2.35</mml:mn> <mml:mo>∘</mml:mo> </mml:msup> </mml:math> ) directly while preserving their intrinsic electronic states. Our high-resolution scanning tunneling spectroscopy (STS) measurements detected the extremely weak valence band at the K-valley, in agreement with large-scale density functional theory (DFT) calculations. This work not only establishes a framework for studying air-sensitive quantum materials but also provides fundamental insights into moiré-engineered correlated and topological states in van der Waals heterostructures.