Enhanced ferromagnetism in monolayer Cr2Te3 via topological insulator coupling

Yunbo Ou; Murod Mirzhalilov; Norbert M. Nemes; Jose L. Martinez; Mirko Rocci; Alexander Duong; Austin Akey; Alexandre C. Foucher; Wenbo Ge; Dhavala Suri; Yiping Wang; Haile Ambaye; Jong Keum; Mohit Randeria; Nandini Trivedi; Kenneth S. Burch; David C. Bell; Frances M. Ross; Weida Wu; Don Heiman; Valeria Lauter; Jagadeesh S. Moodera; Hang Chi

doi:10.1088/1361-6633/add9c5

Enhanced ferromagnetism in monolayer Cr₂Te₃ via topological insulator coupling

Yunbo Ou, Murod Mirzhalilov, Norbert M. Nemes, Jose L. Martinez, Mirko Rocci, Alexander Duong, Austin Akey, Alexandre C. Foucher, Wenbo Ge, Dhavala Suri, Yiping Wang, Haile Ambaye, Jong Keum, Mohit Randeria, Nandini Trivedi, Kenneth S. Burch, David C. Bell, Frances M. Ross, Weida Wu, Don HeimanValeria Lauter, Jagadeesh S. Moodera, Hang Chi

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

Abstract

Exchange-coupled interfaces are pivotal in exploiting two-dimensional (2D) ferromagnetism. Due to the extraordinary correlations among charge, spin, orbital and lattice degrees of freedom, layered magnetic transition metal chalcogenides (TMCs) bode well for exotic topological phenomena. Here we report the realization of wafer-scale Cr₂Te₃ down to monolayer (ML) on insulating SrTiO₃(111) and/or Al₂O₃(001) substrates using molecular beam epitaxy. Robust ferromagnetism persists in the 2D limit. In particular, the Curie temperature T_C of 2 ML Cr₂Te₃ increases from 100 K to ∼120 K when proximitized to topological insulator (TI) (Bi,Sb)₂Te₃, with substantially boosted magnetization as observed via polarized neutron reflectometry. Our experiments and theory strongly indicate that the Bloembergen-Rowland interaction is likely universal underlying T_C enhancement in TI-coupled magnetic heterostructures. The topological-surface-enhanced magnetism in 2D TMC enables further exchange coupling physics and quantum hybrid studies, including paving the way to realize interface-modulated topological electronics.

Original language	English
Article number	060501
Journal	Reports on Progress in Physics
Volume	88
Issue number	6
DOIs	https://doi.org/10.1088/1361-6633/add9c5
State	Published - Jun 1 2025

Funding

This work was supported by Army Research Office (ARO W911NF-20-2-0061), the National Science Foundation (NSF-DMR 2218550), Office of Naval Research (N00014-20-1-2306). H C acknowledges support of the Canada Research Chairs (CRC) Program, and the Natural Sciences and Engineering Research Council of Canada (NSERC), Discovery Grant RGPIN-2024-06497 and ALLRP 592642-2024. Y O, D S, J S M and D C B thank the Center for Integrated Quantum Materials (NSF-DMR 1231319) for financial support. This work made use of the MIT Materials Research Laboratory. D H thanks support from NSF-DMR 1905662 and the Air Force Office of Scientific Research Award No. FA9550-20-1-0247. N M N and J L M were supported by Ministerio de Ciencia e Innovacion, Spain, with Grant Numbers MAT2017-84496-R, PID2021-122477OB-I00, TED2021-129254B-C21 and TED2021-129254B-C22. M R received funding from the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement EuSuper No. 796603. The STEM work was performed in part at the Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Coordinated Infrastructure Network (NNCI), which is supported by NSF Award No. 1541959. A C F is supported by the MIT-IBM Watson AI Lab. This work was carried out in part through the use of MIT.nano\u2019s facilities. The MFM studies at Rutgers were supported by the Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, U.S. Department of Energy under Award No. DE-SC0018153. The Raman measurements of Y W and K S B were performed with support from the Air Force Office of Scientific Research under Award No. FA9550-24-1-011. This research used resources at the Spallation Neutron Source, a Department of Energy Office of Science User Facility operated by the Oak Ridge National Laboratory (ORNL). Neutron reflectometry measurements, beamtime proposal IPTS-24447, were carried out on the Magnetism Reflectometer at the SNS, which is sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, DOE. XRR measurements were conducted at the CNMS at ORNL, which is a DOE Office of Science User Facility. M M, M Ra and N T were supported by the NSF Materials Research Science and Engineering Center Grant No. DMR-2011876. N T thanks K Lee for discussions. Notice: This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan []. This work was supported by Army Research Office (ARO W911NF-20-2-0061), the National Science Foundation (NSF-DMR 2218550), Office of Naval Research (N00014-20-1-2306). H C acknowledges support of the Canada Research Chairs (CRC) Program, and the Natural Sciences and Engineering Research Council of Canada (NSERC), Discovery Grant RGPIN-2024-06497 and ALLRP 592642-2024. Y O, D S, J S M and D C B thank the Center for Integrated Quantum Materials (NSF-DMR 1231319) for financial support. This work made use of the MIT Materials Research Laboratory. D H thanks support from NSF-DMR 1905662 and the Air Force Office of Scientific Research Award No. FA9550-20-1-0247. N M N and J L M were supported by Ministerio de Ciencia e Innovacion, Spain, with Grant Numbers MAT2017-84496-R, PID2021-122477OB-I00, TED2021-129254B-C21 and TED2021-129254B-C22. M R received funding from the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement EuSuper No. 796603. The STEM work was performed in part at the Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Coordinated Infrastructure Network (NNCI), which is supported by NSF Award No. 1541959. A C F is supported by the MIT-IBM Watson AI Lab. This work was carried out in part through the use of MIT.nano\u2019s facilities. The MFM studies at Rutgers were supported by the Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, U.S. Department of Energy under Award No. DE-SC0018153. The Raman measurements of Y W and K S B were performed with support from the Air Force Office of Scientific Research under Award No. FA9550-24-1-011. This research used resources at the Spallation Neutron Source, a Department of Energy Office of Science User Facility operated by the Oak Ridge National Laboratory (ORNL). Neutron reflectometry measurements, beamtime proposal IPTS-24447, were carried out on the Magnetism Reflectometer at the SNS, which is sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, DOE. XRR measurements were conducted at the CNMS at ORNL, which is a DOE Office of Science User Facility. M M, M Ra and N T were supported by the NSF Materials Research Science and Engineering Center Grant No. DMR-2011876. N T thanks K Lee for discussions. Notice: This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan [62].

Keywords

exchange coupling
molecular beam epitaxy
topological materials
transition metal chalcogenides
two-dimensional magnetism

Access to Document

10.1088/1361-6633/add9c5

Cite this

Ou, Y., Mirzhalilov, M., Nemes, N. M., Martinez, J. L., Rocci, M., Duong, A., Akey, A., Foucher, A. C., Ge, W., Suri, D., Wang, Y., Ambaye, H., Keum, J., Randeria, M., Trivedi, N., Burch, K. S., Bell, D. C., Ross, F. M., Wu, W., ... Chi, H. (2025). Enhanced ferromagnetism in monolayer Cr₂Te₃ via topological insulator coupling. Reports on Progress in Physics, 88(6), Article 060501. https://doi.org/10.1088/1361-6633/add9c5

@article{3589fad347214956b92093b452e28684,

title = "Enhanced ferromagnetism in monolayer Cr2Te3 via topological insulator coupling",

abstract = "Exchange-coupled interfaces are pivotal in exploiting two-dimensional (2D) ferromagnetism. Due to the extraordinary correlations among charge, spin, orbital and lattice degrees of freedom, layered magnetic transition metal chalcogenides (TMCs) bode well for exotic topological phenomena. Here we report the realization of wafer-scale Cr2Te3 down to monolayer (ML) on insulating SrTiO3(111) and/or Al2O3(001) substrates using molecular beam epitaxy. Robust ferromagnetism persists in the 2D limit. In particular, the Curie temperature TC of 2 ML Cr2Te3 increases from 100 K to ∼120 K when proximitized to topological insulator (TI) (Bi,Sb)2Te3, with substantially boosted magnetization as observed via polarized neutron reflectometry. Our experiments and theory strongly indicate that the Bloembergen-Rowland interaction is likely universal underlying TC enhancement in TI-coupled magnetic heterostructures. The topological-surface-enhanced magnetism in 2D TMC enables further exchange coupling physics and quantum hybrid studies, including paving the way to realize interface-modulated topological electronics.",

keywords = "exchange coupling, molecular beam epitaxy, topological materials, transition metal chalcogenides, two-dimensional magnetism",

author = "Yunbo Ou and Murod Mirzhalilov and Nemes, {Norbert M.} and Martinez, {Jose L.} and Mirko Rocci and Alexander Duong and Austin Akey and Foucher, {Alexandre C.} and Wenbo Ge and Dhavala Suri and Yiping Wang and Haile Ambaye and Jong Keum and Mohit Randeria and Nandini Trivedi and Burch, {Kenneth S.} and Bell, {David C.} and Ross, {Frances M.} and Weida Wu and Don Heiman and Valeria Lauter and Moodera, {Jagadeesh S.} and Hang Chi",

note = "Publisher Copyright: {\textcopyright} 2025 The Author(s). Published by IOP Publishing Ltd.",

year = "2025",

month = jun,

day = "1",

doi = "10.1088/1361-6633/add9c5",

language = "English",

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Ou, Y, Mirzhalilov, M, Nemes, NM, Martinez, JL, Rocci, M, Duong, A, Akey, A, Foucher, AC, Ge, W, Suri, D, Wang, Y, Ambaye, H , Keum, J, Randeria, M, Trivedi, N, Burch, KS, Bell, DC, Ross, FM, Wu, W, Heiman, D, Lauter, V, Moodera, JS & Chi, H 2025, 'Enhanced ferromagnetism in monolayer Cr₂Te₃ via topological insulator coupling', Reports on Progress in Physics, vol. 88, no. 6, 060501. https://doi.org/10.1088/1361-6633/add9c5

TY - JOUR

T1 - Enhanced ferromagnetism in monolayer Cr2Te3 via topological insulator coupling

AU - Ou, Yunbo

AU - Mirzhalilov, Murod

AU - Nemes, Norbert M.

AU - Martinez, Jose L.

AU - Rocci, Mirko

AU - Duong, Alexander

AU - Akey, Austin

AU - Foucher, Alexandre C.

AU - Ge, Wenbo

AU - Suri, Dhavala

AU - Wang, Yiping

AU - Ambaye, Haile

AU - Keum, Jong

AU - Randeria, Mohit

AU - Trivedi, Nandini

AU - Burch, Kenneth S.

AU - Bell, David C.

AU - Ross, Frances M.

AU - Wu, Weida

AU - Heiman, Don

AU - Lauter, Valeria

AU - Moodera, Jagadeesh S.

AU - Chi, Hang

PY - 2025/6/1

Y1 - 2025/6/1

N2 - Exchange-coupled interfaces are pivotal in exploiting two-dimensional (2D) ferromagnetism. Due to the extraordinary correlations among charge, spin, orbital and lattice degrees of freedom, layered magnetic transition metal chalcogenides (TMCs) bode well for exotic topological phenomena. Here we report the realization of wafer-scale Cr2Te3 down to monolayer (ML) on insulating SrTiO3(111) and/or Al2O3(001) substrates using molecular beam epitaxy. Robust ferromagnetism persists in the 2D limit. In particular, the Curie temperature TC of 2 ML Cr2Te3 increases from 100 K to ∼120 K when proximitized to topological insulator (TI) (Bi,Sb)2Te3, with substantially boosted magnetization as observed via polarized neutron reflectometry. Our experiments and theory strongly indicate that the Bloembergen-Rowland interaction is likely universal underlying TC enhancement in TI-coupled magnetic heterostructures. The topological-surface-enhanced magnetism in 2D TMC enables further exchange coupling physics and quantum hybrid studies, including paving the way to realize interface-modulated topological electronics.

AB - Exchange-coupled interfaces are pivotal in exploiting two-dimensional (2D) ferromagnetism. Due to the extraordinary correlations among charge, spin, orbital and lattice degrees of freedom, layered magnetic transition metal chalcogenides (TMCs) bode well for exotic topological phenomena. Here we report the realization of wafer-scale Cr2Te3 down to monolayer (ML) on insulating SrTiO3(111) and/or Al2O3(001) substrates using molecular beam epitaxy. Robust ferromagnetism persists in the 2D limit. In particular, the Curie temperature TC of 2 ML Cr2Te3 increases from 100 K to ∼120 K when proximitized to topological insulator (TI) (Bi,Sb)2Te3, with substantially boosted magnetization as observed via polarized neutron reflectometry. Our experiments and theory strongly indicate that the Bloembergen-Rowland interaction is likely universal underlying TC enhancement in TI-coupled magnetic heterostructures. The topological-surface-enhanced magnetism in 2D TMC enables further exchange coupling physics and quantum hybrid studies, including paving the way to realize interface-modulated topological electronics.

KW - exchange coupling

KW - molecular beam epitaxy

KW - topological materials

KW - transition metal chalcogenides

KW - two-dimensional magnetism

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