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HL: Fachverband Halbleiterphysik

HL 36: Poster III

HL 36.38: Poster

Wednesday, March 20, 2024, 18:00–20:30, Poster E

Cryogenic nano-imaging of the metal to charge density wave transition in NbSe2 — •Monica Kolek Martinez de Azagra, Francesca Falorsi, Christian Eckel, and Thomas Weitz — Georg-August-Universität Göttingen

The transition metal dichalcogenide (TMDC) NbSe2 exhibits a metallic, charge density wave (CDW) - the periodic modulation of electron densities and lattice atoms - and a superconducting phase. The transition between these phases can be tuned by temperature variation. Previous studies have shown that the critical temperatures TCDW for the CDW transition and TC for the superconductivity are layer dependent. While calculations have shown that with decreasing layer thickness the CDW order is enhanced with a gain in energy [1], experimental results contradict each other regarding the TCDW for few-layer and bulk NbSe2. [2,3] Here, we present our preliminary results on the investigation of 2H-NbSe2 using a cryogenic scanning near-field microscope (SNOM), to image the layer-dependent TCDW. Using SNOM we are able to provide real-space images while probing the dielectric function of the NbSe2 few-layer flakes with nanometer resolution. Subsequently, we will be able to verify our results using transport measurements in situ.

Keywords: NbSe2; 2D materials; CDW; SNOM; scanning near-field optical microscopy