Direct observation of the energy gain underpinning ferromagnetic superexchange in the electronic structure of CrGeTe3

Matthew D. Watson; Igor Marković; Federico Mazzola; Akhil Rajan; Edgar A. Morales; David M. Burn; Thorsten Hesjedal; Gerrit Van Der Laan; Saumya Mukherjee; Timur K. Kim; Chiara Bigi; Ivana Vobornik; Monica Ciomaga Hatnean; Geetha Balakrishnan; Philip D.C. King

doi:10.1103/PhysRevB.101.205125

Direct observation of the energy gain underpinning ferromagnetic superexchange in the electronic structure of CrGeTe₃

Matthew D. Watson^*, Igor Marković, Federico Mazzola, Akhil Rajan, Edgar A. Morales, David M. Burn, Thorsten Hesjedal, Gerrit Van Der Laan, Saumya Mukherjee, Timur K. Kim, Chiara Bigi, Ivana Vobornik, Monica Ciomaga Hatnean, Geetha Balakrishnan, Philip D.C. King

^*Corresponding author for this work

Physics and Astronomy

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

18 Citations (Scopus)

Abstract

We investigate the temperature-dependent electronic structure of the van der Waals ferromagnet, CrGeTe₃. Using angle-resolved photoemission spectroscopy, we identify atomic-and orbital-specific band shifts upon cooling through TC. From these, together with X-ray absorption spectroscopy and X-ray magnetic circular dichroism measurements, we identify the states created by a covalent bond between the Te 5p and the Cr eg orbitals as the primary driver of the ferromagnetic ordering in this system, while it is the Cr t2g states that carry the majority of the spin moment. The t2g states furthermore exhibit a marked bandwidth increase and a remarkable lifetime enhancement upon entering the ordered phase, pointing to a delicate interplay between localized and itinerant states in this family of layered ferromagnets.

Original language	English
Article number	205125
Journal	Physical Review B
Volume	101
Issue number	20
DOIs	https://doi.org/10.1103/PhysRevB.101.205125
Publication status	Published - 15 May 2020

Bibliographical note

Funding Information:
We gratefully acknowledge The Leverhulme Trust (Grant No. RL-2016-006), The Royal Society, and the European Research Council (Grant No. ERC-714193-QUESTDO) for support. We thank Diamond Light Source for access to beamlines I05 (Proposals No. SI21986 and No. NT22794-3) and I10 (Proposal No. MM23785) and Elettra synchrotron for access to the APE beamline, which all contributed to the results presented here. This work has been partly performed in the framework of the Nanoscience Foundry and Fine Analysis (NFFA-MIUR, Italy) facility. I.M. and E.A.M. acknowledge financial support by the International Max Planck Research School for Chemistry and Physics of Quantum Materials (IMPRS-CPQM). The work at the University of Warwick was funded by EPSRC, UK through Grant EP/T005963/1.

Funding Information:
We thank C. Cacho, C. Hooley, and S. Soltani for useful discussions. We thank G. Vinai and J. Fuji for support during beamtime measurements. We gratefully acknowledge The Leverhulme Trust (Grant No. RL-2016-006), The Royal Society, and the European Research Council (Grant No. ERC-714193-QUESTDO) for support. We thank Diamond Light Source for access to beamlines I05 (Proposals No. SI21986 and No. NT22794-3) and I10 (Proposal No. MM23785) and Elettra synchrotron for access to the APE beamline, which all contributed to the results presented here. This work has been partly performed in the framework of the Nanoscience Foundry and Fine Analysis (NFFA-MIUR, Italy) facility. I.M. and E.A.M. acknowledge financial support by the International Max Planck Research School for Chemistry and Physics of Quantum Materials (IMPRS-CPQM). The work at the University of Warwick was funded by EPSRC, UK through Grant EP/T005963/1. The research data supporting this publication can be accessed at the University of St Andrews Research Portal .

Publisher Copyright:
© 2020 American Physical Society.

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics

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10.1103/PhysRevB.101.205125

Cite this

Watson, M. D., Marković, I., Mazzola, F., Rajan, A., Morales, E. A., Burn, D. M., Hesjedal, T., Van Der Laan, G., Mukherjee, S., Kim, T. K., Bigi, C., Vobornik, I., Ciomaga Hatnean, M., Balakrishnan, G., & King, P. D. C. (2020). Direct observation of the energy gain underpinning ferromagnetic superexchange in the electronic structure of CrGeTe₃. Physical Review B, 101(20), Article 205125. https://doi.org/10.1103/PhysRevB.101.205125

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title = "Direct observation of the energy gain underpinning ferromagnetic superexchange in the electronic structure of CrGeTe3",

abstract = "We investigate the temperature-dependent electronic structure of the van der Waals ferromagnet, CrGeTe3. Using angle-resolved photoemission spectroscopy, we identify atomic-and orbital-specific band shifts upon cooling through TC. From these, together with X-ray absorption spectroscopy and X-ray magnetic circular dichroism measurements, we identify the states created by a covalent bond between the Te 5p and the Cr eg orbitals as the primary driver of the ferromagnetic ordering in this system, while it is the Cr t2g states that carry the majority of the spin moment. The t2g states furthermore exhibit a marked bandwidth increase and a remarkable lifetime enhancement upon entering the ordered phase, pointing to a delicate interplay between localized and itinerant states in this family of layered ferromagnets.",

author = "Watson, {Matthew D.} and Igor Markovi{\'c} and Federico Mazzola and Akhil Rajan and Morales, {Edgar A.} and Burn, {David M.} and Thorsten Hesjedal and {Van Der Laan}, Gerrit and Saumya Mukherjee and Kim, {Timur K.} and Chiara Bigi and Ivana Vobornik and {Ciomaga Hatnean}, Monica and Geetha Balakrishnan and King, {Philip D.C.}",

note = "Funding Information: We gratefully acknowledge The Leverhulme Trust (Grant No. RL-2016-006), The Royal Society, and the European Research Council (Grant No. ERC-714193-QUESTDO) for support. We thank Diamond Light Source for access to beamlines I05 (Proposals No. SI21986 and No. NT22794-3) and I10 (Proposal No. MM23785) and Elettra synchrotron for access to the APE beamline, which all contributed to the results presented here. This work has been partly performed in the framework of the Nanoscience Foundry and Fine Analysis (NFFA-MIUR, Italy) facility. I.M. and E.A.M. acknowledge financial support by the International Max Planck Research School for Chemistry and Physics of Quantum Materials (IMPRS-CPQM). The work at the University of Warwick was funded by EPSRC, UK through Grant EP/T005963/1. Funding Information: We thank C. Cacho, C. Hooley, and S. Soltani for useful discussions. We thank G. Vinai and J. Fuji for support during beamtime measurements. We gratefully acknowledge The Leverhulme Trust (Grant No. RL-2016-006), The Royal Society, and the European Research Council (Grant No. ERC-714193-QUESTDO) for support. We thank Diamond Light Source for access to beamlines I05 (Proposals No. SI21986 and No. NT22794-3) and I10 (Proposal No. MM23785) and Elettra synchrotron for access to the APE beamline, which all contributed to the results presented here. This work has been partly performed in the framework of the Nanoscience Foundry and Fine Analysis (NFFA-MIUR, Italy) facility. I.M. and E.A.M. acknowledge financial support by the International Max Planck Research School for Chemistry and Physics of Quantum Materials (IMPRS-CPQM). The work at the University of Warwick was funded by EPSRC, UK through Grant EP/T005963/1. The research data supporting this publication can be accessed at the University of St Andrews Research Portal . Publisher Copyright: {\textcopyright} 2020 American Physical Society.",

year = "2020",

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doi = "10.1103/PhysRevB.101.205125",

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Watson, MD, Marković, I, Mazzola, F, Rajan, A, Morales, EA, Burn, DM, Hesjedal, T, Van Der Laan, G, Mukherjee, S, Kim, TK, Bigi, C, Vobornik, I, Ciomaga Hatnean, M, Balakrishnan, G & King, PDC 2020, 'Direct observation of the energy gain underpinning ferromagnetic superexchange in the electronic structure of CrGeTe₃', Physical Review B, vol. 101, no. 20, 205125. https://doi.org/10.1103/PhysRevB.101.205125

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T1 - Direct observation of the energy gain underpinning ferromagnetic superexchange in the electronic structure of CrGeTe3

AU - Watson, Matthew D.

AU - Marković, Igor

AU - Mazzola, Federico

AU - Rajan, Akhil

AU - Morales, Edgar A.

AU - Burn, David M.

AU - Hesjedal, Thorsten

AU - Van Der Laan, Gerrit

AU - Mukherjee, Saumya

AU - Kim, Timur K.

AU - Bigi, Chiara

AU - Vobornik, Ivana

AU - Ciomaga Hatnean, Monica

AU - Balakrishnan, Geetha

AU - King, Philip D.C.

N1 - Funding Information: We gratefully acknowledge The Leverhulme Trust (Grant No. RL-2016-006), The Royal Society, and the European Research Council (Grant No. ERC-714193-QUESTDO) for support. We thank Diamond Light Source for access to beamlines I05 (Proposals No. SI21986 and No. NT22794-3) and I10 (Proposal No. MM23785) and Elettra synchrotron for access to the APE beamline, which all contributed to the results presented here. This work has been partly performed in the framework of the Nanoscience Foundry and Fine Analysis (NFFA-MIUR, Italy) facility. I.M. and E.A.M. acknowledge financial support by the International Max Planck Research School for Chemistry and Physics of Quantum Materials (IMPRS-CPQM). The work at the University of Warwick was funded by EPSRC, UK through Grant EP/T005963/1. Funding Information: We thank C. Cacho, C. Hooley, and S. Soltani for useful discussions. We thank G. Vinai and J. Fuji for support during beamtime measurements. We gratefully acknowledge The Leverhulme Trust (Grant No. RL-2016-006), The Royal Society, and the European Research Council (Grant No. ERC-714193-QUESTDO) for support. We thank Diamond Light Source for access to beamlines I05 (Proposals No. SI21986 and No. NT22794-3) and I10 (Proposal No. MM23785) and Elettra synchrotron for access to the APE beamline, which all contributed to the results presented here. This work has been partly performed in the framework of the Nanoscience Foundry and Fine Analysis (NFFA-MIUR, Italy) facility. I.M. and E.A.M. acknowledge financial support by the International Max Planck Research School for Chemistry and Physics of Quantum Materials (IMPRS-CPQM). The work at the University of Warwick was funded by EPSRC, UK through Grant EP/T005963/1. The research data supporting this publication can be accessed at the University of St Andrews Research Portal . Publisher Copyright: © 2020 American Physical Society.

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N2 - We investigate the temperature-dependent electronic structure of the van der Waals ferromagnet, CrGeTe3. Using angle-resolved photoemission spectroscopy, we identify atomic-and orbital-specific band shifts upon cooling through TC. From these, together with X-ray absorption spectroscopy and X-ray magnetic circular dichroism measurements, we identify the states created by a covalent bond between the Te 5p and the Cr eg orbitals as the primary driver of the ferromagnetic ordering in this system, while it is the Cr t2g states that carry the majority of the spin moment. The t2g states furthermore exhibit a marked bandwidth increase and a remarkable lifetime enhancement upon entering the ordered phase, pointing to a delicate interplay between localized and itinerant states in this family of layered ferromagnets.

AB - We investigate the temperature-dependent electronic structure of the van der Waals ferromagnet, CrGeTe3. Using angle-resolved photoemission spectroscopy, we identify atomic-and orbital-specific band shifts upon cooling through TC. From these, together with X-ray absorption spectroscopy and X-ray magnetic circular dichroism measurements, we identify the states created by a covalent bond between the Te 5p and the Cr eg orbitals as the primary driver of the ferromagnetic ordering in this system, while it is the Cr t2g states that carry the majority of the spin moment. The t2g states furthermore exhibit a marked bandwidth increase and a remarkable lifetime enhancement upon entering the ordered phase, pointing to a delicate interplay between localized and itinerant states in this family of layered ferromagnets.

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