Dresden 2026 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 65: 2D materials: Stacking and heterostructures – Poster (joint session O/TT)

TT 65.4: Poster

Wednesday, March 11, 2026, 18:00–20:00, P2

Preparation of quasi-freestanding few-layer samples of 2D materials — •Seyedeh Helya Alaei, Hanna Shirin Pulikkal Hamza, Mashood Tariq Mir, Lukas Nöding, Ahmed Hassanien, Arne Senftleben, Jochen Mikosch, and Thomas Baumert — University of Kassel, Institute of Physics, 34132 Kassel, Germany

Two-dimensional (2D) materials have garnered significant attention in the last two decades and have been analyzed using various methods in the fields of materials science and physics. To study the dynamic behavior of 2D materials upon irradiation with femtosecond laser pulses using ultrafast electron diffraction, it is necessary to isolate few-layer structures from bulk crystals and prepare them in a quasi-freestanding manner. Due to the weak van-der-Waals forces between the layers relative to the in-plane forces of the structure, mechanical exfoliation is a commonly used method. However, the transfer is challenging, due to the thinness of the flake and the adhesive force between the flake and the surface. Our preparation involves three major steps: (1) exfoliation using adhesive tape and viscoelastic gel, (2) isolation of 2D material nanosheets with thicknesses ranging from 3 to 50 nm, and (3) transfer onto a standard sample mesh of transmission electron microscopy with a high success rate. The transfer exploits liquid-solid phase transitions of a soluble wax-like material. In this ongoing study, the 2D ferromagnetic material Fe5GeTe2 has been of interest. We will discuss the different steps in detail and the challenges associated with the preparation of this material, including the fragility of the crystals due to oxidation and the partially covalent out-of-plane forces.

Keywords: 2D materials; Sample preparation; Mechanical exfoliation; van-der-Waals structures; Ultrafast electron diffraction