Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 40: 2D Materials and Heterostructures: Magnetic Properties

HL 40.5: Talk

Thursday, March 21, 2024, 10:30–10:45, EW 201

Optical signatures of the magnetic order in CrSBr — •Marie-Christin Heißenbüttel¹, Pierre-Maurice Piel², Julian Klein³, Thorsten Deilmann¹, Ursula Wurstbauer², and Michael Rohlfing¹ — ¹Institute of Solid State Theory, University of Münster, Germany — ²Physical Institute, University of Münster, Germany — ³Department of Materials Science and Engineering, MIT, Massachusetts, USA

Controlling excitons in van der Waals coupled systems is a key idea to reveal tailored properties for the development of opto-electronic devices. Exciton energy and character in antiferromagnetic multilayer CrSBr can be controlled by an external magnetic field switching the internal magnetization to a ferromagnetic order. This modifies the optical response and we observe in our ab-initio GW/BSE calculations a distinct redshift, in accordance with corresponding measurements. We set up a minimal model to explain and convey the underlying physical mechanisms. Depending on the external field the coupling of adjacent layers is changed, shifting electronic states linearly in energy and excitons quadratically with respect to the field strength. While our results are generally valid for antiferromagnetic layered magnets, we uncover that the lowest excitation in CrSBr is optically dark and its detuning can also be controlled by the magnetic field.

Keywords: CrSBr; charge transfer excitons; magnetic materials; optical properties; interlayer coupling