Regensburg 2022 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 35: 2D Materials 8 (joint session DS/CPP)

CPP 35.3: Vortrag

Donnerstag, 8. September 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).