Correlated quantum phenomena in one-dimensional (1D) systems that exhibit competing electronic and magnetic order are of strong interest for the study of fundamental interactions and excitations, such as Tomonaga-Luttinger liquids and topological orders and defects with properties completely different from the quasiparticles expected in their higher-dimensional counterparts. However, clean 1D electronic systems are difficult to realize experimentally, particularly for magnetically ordered systems. Here, we show that the van der Waals layered magnetic semiconductor CrSBr behaves like a quasi-1D material embedded in a magnetically ordered environment. The strong 1D electronic character originates from the Cr-S chains and the combination of weak interlayer hybridization and anisotropy in effective mass and dielectric screening, with an effective electron mass ratio of mXe/mYe ∼ 50. This extreme anisotropy experimentally manifests in strong electron-phonon and exciton-phonon interactions, a Peierls-like structural instability, and a Fano resonance from a van Hove singularity of similar strength to that of metallic carbon nanotubes. Moreover, because of the reduced dimensionality and interlayer coupling, CrSBr hosts spectrally narrow (1 meV) excitons of high binding energy and oscillator strength that inherit the 1D character. Overall, CrSBr is best understood as a stack of weakly hybridized monolayers and appears to be an experimentally attractive candidate for the study of exotic exciton and 1D-correlated many-body physics in the presence of magnetic order.

Bremen Center for Computational Materials Science University of Bremen 28359 Bremen Germany

Center for Visualizing Catalytic Processes Department of Physics Technical University of Denmark DK 2800 Kgs Lyngby Denmark

College of Letters and Science UCLA Los Angeles California 90095 United States

Department of Electrical and Computer Engineering Department of Physics University of Michigan Ann Arbor Michigan 48109 United States

Department of Inorganic Chemistry University of Chemistry and Technology Prague Technická 5 166 28 Prague 6 Czech Republic

Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge Massachusetts 02139 United States

Department of Physics City College of New York New York New York 10031 United States

Department of Physics The Graduate Center City University of New York New York New York 10016 United States

Institut für Festkörpertheorie Westfälische Wilhelms Universität Münster 48149 Münster Germany

Institut für Theoretische Physik Universität Bremen P O Box 330 440 28334 Bremen Germany

Institute of Physics and Center for Nanotechnology University of Münster 48149 Münster Germany

John A Paulson School of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 United States

MIT nano Massachusetts Institute of Technology Cambridge Massachusetts 02139 United States

Photonics Initiative CUNY Advanced Science Research Center New York New York 10031 United States

Physics Program Graduate Center City University of New York New York New York 10026 United States

QuTech Delft University of Technology 2600 GA Delft The Netherlands

References provided by Crossref.org

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Strong Exciton-Phonon Coupling as a Fingerprint of Magnetic Ordering in van der Waals Layered CrSBr

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