Steering Large Magnetic Exchange Coupling in Nanographenes near the Closed-Shell to Open-Shell Transition.

Biswas, Kalyan; Soler, Diego; Mishra, Shantanu; Chen, Qiang; Yao, Xuelin; Sánchez-Grande, Ana; Eimre, Kristjan; Mutombo, Pingo; Martín-Fuentes, Cristina; Lauwaet, Koen; Gallego, José M; Ruffieux, Pascal; Pignedoli, Carlo A; Müllen, Klaus; Miranda, Rodolfo; Urgel, José I; Narita, Akimitsu; Fasel, Roman; Jelínek, Pavel and Écija, David (2023). Steering Large Magnetic Exchange Coupling in Nanographenes near the Closed-Shell to Open-Shell Transition. Journal of the American Chemical Society, 145(5), pp. 2968-2974. American Chemical Society 10.1021/jacs.2c11431

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The design of open-shell carbon-based nanomaterials is at the vanguard of materials science, steered by their beneficial magnetic properties like weaker spin-orbit coupling than that of transition metal atoms and larger spin delocalization, which are of potential relevance for future spintronics and quantum technologies. A key parameter in magnetic materials is the magnetic exchange coupling (MEC) between unpaired spins, which should be large enough to allow device operation at practical temperatures. In this work, we theoretically and experimentally explore three distinct families of nanographenes (NGs) (A, B, and C) featuring majority zigzag peripheries. Through many-body calculations, we identify a transition from a closed-shell ground state to an open-shell ground state upon an increase of the molecular size. Our predictions indicate that the largest MEC for open-shell NGs occurs in proximity to the transition between closed-shell and open-shell states. Such predictions are corroborated by the on-surface syntheses and structural, electronic, and magnetic characterizations of three NGs (A[3,5], B[4,5], and C[4,3]), which are the smallest open-shell systems in their respective chemical families and are thus located the closest to the transition boundary. Notably, two of the NGs (B[4,5] and C[4,3]) feature record values of MEC (close to 200 meV) measured on the Au(111) surface. Our strategy for maximizing the MEC provides perspectives for designing carbon nanomaterials with robust magnetic ground states.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP)

UniBE Contributor:

Fasel, Roman

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry

ISSN:

0002-7863

Publisher:

American Chemical Society

Language:

English

Submitter:

Pubmed Import

Date Deposited:

01 Feb 2023 12:00

Last Modified:

09 Feb 2023 00:16

Publisher DOI:

10.1021/jacs.2c11431

PubMed ID:

36708335

BORIS DOI:

10.48350/178049

URI:

https://boris.unibe.ch/id/eprint/178049

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