Spin splitting of dopant edge state in magnetic zigzag graphene nanoribbons

Raymond E Blackwell; Fangzhou Zhao; Erin Brooks; Junmian Zhu; Ilya Piskun; Shenkai Wang; Aidan Delgado; Yea-Lee Lee; Steven G Louie; Felix R Fischer

doi:10.1038/s41586-021-04201-y

Spin splitting of dopant edge state in magnetic zigzag graphene nanoribbons

Nature. 2021 Dec;600(7890):647-652. doi: 10.1038/s41586-021-04201-y. Epub 2021 Dec 22.

Authors

Raymond E Blackwell^#¹, Fangzhou Zhao^#^{2

3}, Erin Brooks¹, Junmian Zhu¹, Ilya Piskun¹, Shenkai Wang¹, Aidan Delgado¹, Yea-Lee Lee², Steven G Louie^{4

5}, Felix R Fischer^{6

7

8}

Affiliations

¹ Department of Chemistry, University of California, Berkeley, CA, USA.
² Department of Physics, University of California, Berkeley, CA, USA.
³ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁴ Department of Physics, University of California, Berkeley, CA, USA. sglouie@berkeley.edu.
⁵ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. sglouie@berkeley.edu.
⁶ Department of Chemistry, University of California, Berkeley, CA, USA. ffischer@berkeley.edu.
⁷ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. ffischer@berkeley.edu.
⁸ Kavli Energy NanoScience Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA, USA. ffischer@berkeley.edu.

^# Contributed equally.

PMID: 34937899
DOI: 10.1038/s41586-021-04201-y

Abstract

Spin-ordered electronic states in hydrogen-terminated zigzag nanographene give rise to magnetic quantum phenomena^1,2 that have sparked renewed interest in carbon-based spintronics^3,4. Zigzag graphene nanoribbons (ZGNRs)-quasi one-dimensional semiconducting strips of graphene bounded by parallel zigzag edges-host intrinsic electronic edge states that are ferromagnetically ordered along the edges of the ribbon and antiferromagnetically coupled across its width^1,2,5. Despite recent advances in the bottom-up synthesis of GNRs featuring symmetry protected topological phases^6-8 and even metallic zero mode bands⁹, the unique magnetic edge structure of ZGNRs has long been obscured from direct observation by a strong hybridization of the zigzag edge states with the surface states of the underlying support^10-15. Here, we present a general technique to thermodynamically stabilize and electronically decouple the highly reactive spin-polarized edge states by introducing a superlattice of substitutional N-atom dopants along the edges of a ZGNR. First-principles GW calculations and scanning tunnelling spectroscopy reveal a giant spin splitting of low-lying nitrogen lone-pair flat bands by an exchange field (~850 tesla) induced by the ferromagnetically ordered edge states of ZGNRs. Our findings directly corroborate the nature of the predicted emergent magnetic order in ZGNRs and provide a robust platform for their exploration and functional integration into nanoscale sensing and logic devices^15-21.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Grants and funding

S10 OD024998/OD/NIH HHS/United States