Spin-valley coupling enhanced high-TC ferromagnetism in a non-van der Waals monolayer Cr2Se3 on graphene

C. W. Chuang; T. Kawakami; K. Sugawara; K. Nakayama; S. Souma; M. Kitamura; K. Amemiya; K. Horiba; H. Kumigashira; G. Kremer; Y. Fagot-Revurat; D. Malterre; C. Bigi; F. Bertran; F. H. Chang; H. J. Lin; C. T. Chen; T. Takahashi; A. Chainani; T. Sato

doi:10.1038/s41467-025-58643-3

Spin-valley coupling enhanced high-T_C ferromagnetism in a non-van der Waals monolayer Cr₂Se₃ on graphene

C. W. Chuang, T. Kawakami, K. Sugawara, K. Nakayama, S. Souma, M. Kitamura, K. Amemiya, K. Horiba, H. Kumigashira, G. Kremer, Y. Fagot-Revurat, D. Malterre, C. Bigi, F. Bertran, F. H. Chang, H. J. Lin, C. T. Chen, T. Takahashi, A. Chainani, T. Sato

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Abstract

Spin-valley magnetic ordering is restricted to layered van der Waals type transition-metal dichalcogenides with ordering temperatures below 55 K. Recent theoretical studies on non-van der Waals structures have predicted spin-valley polarization induced semiconducting ferromagnetic ground states, but experimental validation is missing. We report high-Curie temperature (T_C ~ 225 K) metallic ferromagnetism with spontaneous spin-valley polarization in monolayer Cr₂Se₃ on graphene. Angle-resolved photoemission spectroscopy (ARPES) reveals systematic temperature-dependent energy shifts and splitting of localized Cr 3 d^↑-t_2g bands, accompanied by occupancy of the itinerant Cr 3d-e_g valleys. The t_2g-e_g spin-valley coupling at the K/K’ points of hexagonal Brillouin zone leads to ferromagnetic ordering. Circular dichroism in ARPES shows clear evidence of spin-valley polarized states. Comparison with bilayer and trilayer Cr₂Se₃ reveals the crucial role of valley carrier density in enhancing T_C and provides a guiding principle to realize 2D ferromagnetism at higher temperatures in non-van der Waals materials.

Original language	English
Article number	3448
Journal	Nature Communications
Volume	16
Issue number	1
DOIs	https://doi.org/10.1038/s41467-025-58643-3
Publication status	Published - 2025 Dec

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Chuang, C. W., Kawakami, T., Sugawara, K., Nakayama, K., Souma, S., Kitamura, M., Amemiya, K., Horiba, K., Kumigashira, H., Kremer, G., Fagot-Revurat, Y., Malterre, D., Bigi, C., Bertran, F., Chang, F. H., Lin, H. J., Chen, C. T., Takahashi, T., Chainani, A., & Sato, T. (2025). Spin-valley coupling enhanced high-T_C ferromagnetism in a non-van der Waals monolayer Cr₂Se₃ on graphene. Nature Communications, 16(1), Article 3448. https://doi.org/10.1038/s41467-025-58643-3

@article{f80319cedf894e96927fa73a8c441511,

title = "Spin-valley coupling enhanced high-TC ferromagnetism in a non-van der Waals monolayer Cr2Se3 on graphene",

abstract = "Spin-valley magnetic ordering is restricted to layered van der Waals type transition-metal dichalcogenides with ordering temperatures below 55 K. Recent theoretical studies on non-van der Waals structures have predicted spin-valley polarization induced semiconducting ferromagnetic ground states, but experimental validation is missing. We report high-Curie temperature (TC ~ 225 K) metallic ferromagnetism with spontaneous spin-valley polarization in monolayer Cr2Se3 on graphene. Angle-resolved photoemission spectroscopy (ARPES) reveals systematic temperature-dependent energy shifts and splitting of localized Cr 3 d↑-t2g bands, accompanied by occupancy of the itinerant Cr 3d-eg valleys. The t2g-eg spin-valley coupling at the K/K{\textquoteright} points of hexagonal Brillouin zone leads to ferromagnetic ordering. Circular dichroism in ARPES shows clear evidence of spin-valley polarized states. Comparison with bilayer and trilayer Cr2Se3 reveals the crucial role of valley carrier density in enhancing TC and provides a guiding principle to realize 2D ferromagnetism at higher temperatures in non-van der Waals materials.",

author = "Chuang, {C. W.} and T. Kawakami and K. Sugawara and K. Nakayama and S. Souma and M. Kitamura and K. Amemiya and K. Horiba and H. Kumigashira and G. Kremer and Y. Fagot-Revurat and D. Malterre and C. Bigi and F. Bertran and Chang, {F. H.} and Lin, {H. J.} and Chen, {C. T.} and T. Takahashi and A. Chainani and T. Sato",

note = "Publisher Copyright: {\textcopyright} The Author(s) 2025.",

year = "2025",

month = dec,

doi = "10.1038/s41467-025-58643-3",

language = "English",

volume = "16",

journal = "Nature Communications",

issn = "2041-1723",

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Chuang, CW, Kawakami, T, Sugawara, K , Nakayama, K , Souma, S, Kitamura, M, Amemiya, K, Horiba, K, Kumigashira, H, Kremer, G, Fagot-Revurat, Y, Malterre, D, Bigi, C, Bertran, F, Chang, FH, Lin, HJ, Chen, CT, Takahashi, T, Chainani, A & Sato, T 2025, 'Spin-valley coupling enhanced high-T_C ferromagnetism in a non-van der Waals monolayer Cr₂Se₃ on graphene', Nature Communications, vol. 16, no. 1, 3448. https://doi.org/10.1038/s41467-025-58643-3

TY - JOUR

T1 - Spin-valley coupling enhanced high-TC ferromagnetism in a non-van der Waals monolayer Cr2Se3 on graphene

AU - Chuang, C. W.

AU - Kawakami, T.

AU - Sugawara, K.

AU - Nakayama, K.

AU - Souma, S.

AU - Kitamura, M.

AU - Amemiya, K.

AU - Horiba, K.

AU - Kumigashira, H.

AU - Kremer, G.

AU - Fagot-Revurat, Y.

AU - Malterre, D.

AU - Bigi, C.

AU - Bertran, F.

AU - Chang, F. H.

AU - Lin, H. J.

AU - Chen, C. T.

AU - Takahashi, T.

AU - Chainani, A.

AU - Sato, T.

PY - 2025/12

Y1 - 2025/12

N2 - Spin-valley magnetic ordering is restricted to layered van der Waals type transition-metal dichalcogenides with ordering temperatures below 55 K. Recent theoretical studies on non-van der Waals structures have predicted spin-valley polarization induced semiconducting ferromagnetic ground states, but experimental validation is missing. We report high-Curie temperature (TC ~ 225 K) metallic ferromagnetism with spontaneous spin-valley polarization in monolayer Cr2Se3 on graphene. Angle-resolved photoemission spectroscopy (ARPES) reveals systematic temperature-dependent energy shifts and splitting of localized Cr 3 d↑-t2g bands, accompanied by occupancy of the itinerant Cr 3d-eg valleys. The t2g-eg spin-valley coupling at the K/K’ points of hexagonal Brillouin zone leads to ferromagnetic ordering. Circular dichroism in ARPES shows clear evidence of spin-valley polarized states. Comparison with bilayer and trilayer Cr2Se3 reveals the crucial role of valley carrier density in enhancing TC and provides a guiding principle to realize 2D ferromagnetism at higher temperatures in non-van der Waals materials.

AB - Spin-valley magnetic ordering is restricted to layered van der Waals type transition-metal dichalcogenides with ordering temperatures below 55 K. Recent theoretical studies on non-van der Waals structures have predicted spin-valley polarization induced semiconducting ferromagnetic ground states, but experimental validation is missing. We report high-Curie temperature (TC ~ 225 K) metallic ferromagnetism with spontaneous spin-valley polarization in monolayer Cr2Se3 on graphene. Angle-resolved photoemission spectroscopy (ARPES) reveals systematic temperature-dependent energy shifts and splitting of localized Cr 3 d↑-t2g bands, accompanied by occupancy of the itinerant Cr 3d-eg valleys. The t2g-eg spin-valley coupling at the K/K’ points of hexagonal Brillouin zone leads to ferromagnetic ordering. Circular dichroism in ARPES shows clear evidence of spin-valley polarized states. Comparison with bilayer and trilayer Cr2Se3 reveals the crucial role of valley carrier density in enhancing TC and provides a guiding principle to realize 2D ferromagnetism at higher temperatures in non-van der Waals materials.

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U2 - 10.1038/s41467-025-58643-3

DO - 10.1038/s41467-025-58643-3

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SN - 2041-1723

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JO - Nature Communications

JF - Nature Communications

IS - 1

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ER -

Spin-valley coupling enhanced high-T_C ferromagnetism in a non-van der Waals monolayer Cr₂Se₃ on graphene

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