Observation of Anisotropic Dispersive Dark-Exciton Dynamics in CrSBr

J. Sears; B. Zager; W. He; C. A. Occhialini; Y. Shen; M. Lajer; J. W. Villanova; T. Berlijn; F. Yakhou-Harris; N. B. Brookes; D. G. Chica; X. Roy; E. Baldini; J. Pelliciari; V. Bisogni; S. Johnston; M. Mitrano; M. P.M. Dean

doi:10.1103/fz3h-6jdx

Observation of Anisotropic Dispersive Dark-Exciton Dynamics in CrSBr

J. Sears
, B. Zager
, W. He
, C. A. Occhialini
, Y. Shen
, M. Lajer
, J. W. Villanova
, T. Berlijn
, F. Yakhou-Harris
, N. B. Brookes
, D. G. Chica
, X. Roy
, E. Baldini
, J. Pelliciari
, V. Bisogni
, S. Johnston
, M. Mitrano
, M. P.M. Dean

Nanomaterials Theory Institute

Research output: Contribution to journal › Article › peer-review

Abstract

Many-body excitons in CrSBr are attracting intense interest in view of their highly anisotropic magneto-optical coupling and their potential for novel optical interfaces within spintronic and magnonic devices. Characterizing the orbital character and propagation of these electronic excitations is crucial for understanding and controlling their behavior; however, this information is challenging to access. High resolution resonant inelastic x-ray scattering is a momentum-resolved technique that can address these crucial questions. We present measurements collected at the Cr L3-edge which show a rich spectrum of excitations with a variety of spin-orbital characters. While most of these excitations appear to be localized, the dispersion of the lowest energy dark exciton indicates that it is able to propagate along both the a and b directions within the planes of the crystal. This two-dimensional character is surprising as it contrasts with electrical conductivity and the behavior of the bright exciton, both of which are strongly one dimensional. The discovery of this propagating dark exciton highlights an unusual coexistence of one- and two-dimensional electronic behaviors in CrSBr.

Original language	English
Article number	146503
Journal	Physical Review Letters
Volume	135
Issue number	14
DOIs	https://doi.org/10.1103/fz3h-6jdx
State	Published - Oct 3 2025

Funding

Work at Brookhaven and Harvard is supported by the Office of Basic Energy Sciences, Materials Sciences and Engineering Division, U.S. Department of Energy (DOE) under Contract No. DE-SC0012704. Work at the University of Tennessee (RIXS calculations and interpretation by model Hamiltonian calculations) was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award No. DE-SC0022311. E.B. was supported by the United States Army Research Office (W911NF-23-1-0394). Synthesis work at Columbia University was supported by the Programmable Quantum Materials, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under Award No. DESC0019443. This research used ESRF beam line ID32 under proposal HC5030. Part of this research (T.B.) was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. The work by J.W.V. is supported by the Quantum Science Center (QSC), a National Quantum Information Science Research Center of DOE. We also acknowledge resources made available through BNL/LDRD#19-013. This research used beamline 2-ID of the National Synchrotron Light Source II, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. Work at Brookhaven and Harvard is supported by the Office of Basic Energy Sciences, Materials Sciences and Engineering Division, U.S. Department of Energy (DOE) under Contract No. DE-SC0012704. Work at the University of Tennessee (RIXS calculations and interpretation by model Hamiltonian calculations) was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award No. DE-SC0022311. E. B. was supported by the United States Army Research Office (W911NF-23-1-0394). Synthesis work at Columbia University was supported by the Programmable Quantum Materials, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under Award No. DESC0019443. This research used ESRF beam line ID32 under proposal HC5030. Part of this research (T. B.) was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. The work by J. W. V. is supported by the Quantum Science Center (QSC), a National Quantum Information Science Research Center of DOE. We also acknowledge resources made available through BNL/LDRD#19-013. This research used beamline 2-ID of the National Synchrotron Light Source II, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704.

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Sears, J., Zager, B., He, W., Occhialini, C. A., Shen, Y., Lajer, M., Villanova, J. W., Berlijn, T., Yakhou-Harris, F., Brookes, N. B., Chica, D. G., Roy, X., Baldini, E., Pelliciari, J., Bisogni, V., Johnston, S., Mitrano, M., & Dean, M. P. M. (2025). Observation of Anisotropic Dispersive Dark-Exciton Dynamics in CrSBr. Physical Review Letters, 135(14), Article 146503. https://doi.org/10.1103/fz3h-6jdx

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title = "Observation of Anisotropic Dispersive Dark-Exciton Dynamics in CrSBr",

abstract = "Many-body excitons in CrSBr are attracting intense interest in view of their highly anisotropic magneto-optical coupling and their potential for novel optical interfaces within spintronic and magnonic devices. Characterizing the orbital character and propagation of these electronic excitations is crucial for understanding and controlling their behavior; however, this information is challenging to access. High resolution resonant inelastic x-ray scattering is a momentum-resolved technique that can address these crucial questions. We present measurements collected at the Cr L3-edge which show a rich spectrum of excitations with a variety of spin-orbital characters. While most of these excitations appear to be localized, the dispersion of the lowest energy dark exciton indicates that it is able to propagate along both the a and b directions within the planes of the crystal. This two-dimensional character is surprising as it contrasts with electrical conductivity and the behavior of the bright exciton, both of which are strongly one dimensional. The discovery of this propagating dark exciton highlights an unusual coexistence of one- and two-dimensional electronic behaviors in CrSBr.",

author = "J. Sears and B. Zager and W. He and Occhialini, \{C. A.\} and Y. Shen and M. Lajer and Villanova, \{J. W.\} and T. Berlijn and F. Yakhou-Harris and Brookes, \{N. B.\} and Chica, \{D. G.\} and X. Roy and E. Baldini and J. Pelliciari and V. Bisogni and S. Johnston and M. Mitrano and Dean, \{M. P.M.\}",

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Sears, J, Zager, B, He, W, Occhialini, CA, Shen, Y, Lajer, M, Villanova, JW, Berlijn, T, Yakhou-Harris, F, Brookes, NB, Chica, DG, Roy, X, Baldini, E, Pelliciari, J, Bisogni, V, Johnston, S, Mitrano, M & Dean, MPM 2025, 'Observation of Anisotropic Dispersive Dark-Exciton Dynamics in CrSBr', Physical Review Letters, vol. 135, no. 14, 146503. https://doi.org/10.1103/fz3h-6jdx

TY - JOUR

T1 - Observation of Anisotropic Dispersive Dark-Exciton Dynamics in CrSBr

AU - Sears, J.

AU - Zager, B.

AU - He, W.

AU - Occhialini, C. A.

AU - Shen, Y.

AU - Lajer, M.

AU - Villanova, J. W.

AU - Berlijn, T.

AU - Yakhou-Harris, F.

AU - Brookes, N. B.

AU - Chica, D. G.

AU - Roy, X.

AU - Baldini, E.

AU - Pelliciari, J.

AU - Bisogni, V.

AU - Johnston, S.

AU - Mitrano, M.

AU - Dean, M. P.M.

PY - 2025/10/3

Y1 - 2025/10/3

N2 - Many-body excitons in CrSBr are attracting intense interest in view of their highly anisotropic magneto-optical coupling and their potential for novel optical interfaces within spintronic and magnonic devices. Characterizing the orbital character and propagation of these electronic excitations is crucial for understanding and controlling their behavior; however, this information is challenging to access. High resolution resonant inelastic x-ray scattering is a momentum-resolved technique that can address these crucial questions. We present measurements collected at the Cr L3-edge which show a rich spectrum of excitations with a variety of spin-orbital characters. While most of these excitations appear to be localized, the dispersion of the lowest energy dark exciton indicates that it is able to propagate along both the a and b directions within the planes of the crystal. This two-dimensional character is surprising as it contrasts with electrical conductivity and the behavior of the bright exciton, both of which are strongly one dimensional. The discovery of this propagating dark exciton highlights an unusual coexistence of one- and two-dimensional electronic behaviors in CrSBr.

AB - Many-body excitons in CrSBr are attracting intense interest in view of their highly anisotropic magneto-optical coupling and their potential for novel optical interfaces within spintronic and magnonic devices. Characterizing the orbital character and propagation of these electronic excitations is crucial for understanding and controlling their behavior; however, this information is challenging to access. High resolution resonant inelastic x-ray scattering is a momentum-resolved technique that can address these crucial questions. We present measurements collected at the Cr L3-edge which show a rich spectrum of excitations with a variety of spin-orbital characters. While most of these excitations appear to be localized, the dispersion of the lowest energy dark exciton indicates that it is able to propagate along both the a and b directions within the planes of the crystal. This two-dimensional character is surprising as it contrasts with electrical conductivity and the behavior of the bright exciton, both of which are strongly one dimensional. The discovery of this propagating dark exciton highlights an unusual coexistence of one- and two-dimensional electronic behaviors in CrSBr.

UR - https://www.scopus.com/pages/publications/105019114243

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DO - 10.1103/fz3h-6jdx

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VL - 135

JO - Physical Review Letters

JF - Physical Review Letters

IS - 14

M1 - 146503

ER -

Observation of Anisotropic Dispersive Dark-Exciton Dynamics in CrSBr

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