Regensburg 2022 – scientific programme
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DS: Fachverband Dünne Schichten
DS 22: 2D Materials 8 (joint session DS/CPP)
DS 22.3: Talk
Thursday, September 8, 2022, 10:00–10:15, H17
Layer dependent anisotropic dielectric function of the magnetic semiconductor CrSBr — •Pierre-Maurice Piel1, Margaux Lassaunière1, Julian Klein2, and Ursula Wurstbauer1 — 1Institute of Physics, Muenster University, Germany — 2Department of Materials Science and Engineering, Massachusetts Institute of Technology, USA
The van der Waals (vdW) material CrSBr is a 2D magnetic semiconductor with ferromagnetic ordering within each layer. Adjacent layers, however, are coupled antiferromagnetically. As a vdw semiconductor with a direct band gap, the light matter interaction is determined by strong excitonic resonances that are highly anisotropic in the crystal plane. We experimentally determine the complex dielectric function in the near infrared to visible regime along the two main crystal directions by spectroscopic imaging ellipsometry (SIE) measurements and regression analysis to a multilayer model. Unlike other vdW semiconductors such as MoS2 or WSe2 [1], the rich excitonic signatures in the dielectric function are highly anisotropic and show only minor distinct dependence on the number of layers. Even more striking, we find that the excitonic resonance are better pronounced for multilayer compared to monolayer CrSBr with significantly reduced line-width even at room temperature. [1] Wurstbauer et al. J. Phys. D: Appl. Phys. 50, 173001 (2017).