SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 30: 2D Materials I: Electronic Structure

O 30.2: Vortrag

Dienstag, 28. März 2023, 10:45–11:00, GER 37

Charge density wave in 2H-NbSe₂ studied by combined STM/nc-AFM — •Nikhil Seeja Sivakumar¹, Marion van Midden Mavric¹, Nora Huijgen¹, Umut Kamber², Daniel Wegner¹, Alexander Ako Khajetoorians¹, and Nadine Hauptmann¹ — ¹Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands — ²Department of Physics, Princeton University, USA

Van der Waals materials exhibit interesting quantum phases such as charge density waves (CDW) which originate from an electronic instability along with structural rearrangements. One example is 2H-NbSe₂ which exhibits an incommensurate CDW below 33 K. The origin of the CDW in 2H-NbSe₂ is currently understood to be driven by electron-phonon coupling [1]. To characterize the CDW with atomic scale resolution, Scanning Tunneling Microscopy (STM) is frequently used which is sensitive to the convolution of the geometric structure and the local density of states.

Here, we utilize combined low-temperature STM and non-contact Atomic Force Microscopy (STM/nc-AFM) based on the qPlus design to study the CDW at the surface of 2H-NbSe₂. We detail the distancedependent contrast of the atomic lattice and the CDW in current and frequency shift images. We further compare force spectroscopy data at selected positions of the CDW unit cell and analyze different force contributions.

[1] Flicker, F., van Wezel, J. Nat. Commun. 6, 7034 (2015).