Non-synchronous strain effects on a hetero-bonded van der Waals material CrSBr

Abstract The van der Waals (vdW) material CrSBr exhibits a distinctive hetero-bonded structure, characterized by fence-like and rectangular configurations viewed from different crystallographic orientations. Mechanical deformation of this unique structure can induce significant anisotropic electronic and optical properties. In this study, we systematically investigate the non-synchronous strain response of CrSBr through theoretical and experimental approaches. Our results reveal that the electronic band structure of CrSBr is predominantly governed by the intralayer Cr–S bonds along the b -axis, whereas the characteristic Raman peak <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi mathvariant="normal">A</mml:mi> <mml:mi mathvariant="normal">g</mml:mi> <mml:mn>3</mml:mn> </mml:msubsup> </mml:mrow> </mml:math> arises from interlayer Cr–S bond vibrations in each quasi-monolayer. Notably, the different strain responses of these two types of bonds, stemming from the hetero-bonded architecture, lead to distinct behaviors in photoluminescence (PL) and Raman spectra under uniaxial strain. Specifically, the electronic band structure demonstrates heightened sensitivity to tensile strain along the b -axis, while the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi mathvariant="normal">A</mml:mi> <mml:mi mathvariant="normal">g</mml:mi> <mml:mn>3</mml:mn> </mml:msubsup> </mml:mrow> </mml:math> Raman mode exhibits greater sensitivity to strain along the a -axis. These insights advance the understanding of strain-induced anisotropies in CrSBr and provide valuable guidance for the design of vdW-based optoelectronic devices.