Magnetic Carbon

 

Magnetic Carbon

 

Date: 3^rd April, 2025 (Thursday)

Time:  5 - 6 pm (HKT)

 

Venue: Lecture Theatre P3, Chong Yuet Ming Physics Building

 

Prof. Thomas Heine

 

School of Science

Technische Universität Dresden, Germany

 

Professor Thomas Heine holds a chair professor of theoretical chemistry at Technische Universität Dresden (TU Dresden), Germany. Prof. Heine (PhD 1999, venia legendi 2006 TU Dresden) started his research group in 2008 at Jacobs University Bremen, moved to University of Leipzig in 2015 and to his current position at TU Dresden in 2018. He is a Clarivate Highly Cited Researcher with more than 420 peer-reviewed articles, an h-index of 98 (ISI) / 110 (Google Scholar), and more than 43000 citations. Prof. Heine is elected member of the Review Board of Deutsche Forschungsgemeinschaft (DFG). He is also is an elected member of the Academia Europaea (MAE) and the fellow of the Royal Society of Chemistry (FRSC). Prof. Heine coordinates DFG Priority Program PP 2244 “2D Materials: Physics of van der Waals [hetero]structures”, the DFG Researcher Training Group RTG 2861 “Planar Carbon Lattices”, and the Marie S. Curie European Training Network “2Exciting”. Prof. Heine also holds a prestigious ERC Synergy Grant (2DPolyMembrane) and a DFG Reinhart-Koselleck project (top funding scheme for individuals by DFG).

 

It is generally accepted that carbon is the most versatile element of the periodic table, and it offers a plethora of compounds ranging from biology to materials science. While the list of fascinating properties carbon materials offer is long, they are not yet famous for magnetism.

 

Indeed, most carbon materials are diamagnetic. Defects, dopants and dangling bonds can introduce paramagnetic centers without the potential to generate magnetic ordering. Recently reported magic-angle twisted bilayer graphene may become ferromagnetic due to a half-filled flat band at the fermi level and spin-orbit coupling [1]. A spectacular early report on magnetic carbon in pressurized fullerenes [2] was found to be caused by defects and the paper has been retracted five years later.

 

We propose an alternative concept to generate carbon materials with strongly coupled magnetic centers. Our materials are based on molecular triangulene and its derivatives, aromatic molecules intrinsically carrying one or two unpaired electrons. Using covalent linkages that preserve electron conjugation, we construct two-dimensional polymers with honeycomb-kagome lattice. The magnetic coupling between the monomers is facilitated by the linker groups. This has been examined in detail for the dimers [3]. When extending this concept to 2D polymers, we predict magnetic carbon materials with intriguing electronic structure that includes orbital ferromagnetism, while it maintains the Dirac and flat bands which are characteristic for the honeycomb-kagome lattice of the underlying 2D polymer [4,5].

 

[1]A. A. Sharpe E. J. Fox, A. W. Barnard, J. Finney, K. Watanabe, T. Taniguchi, M. A. Kastner, D. Goldhaber-Gordon, ACS Nano 21, 4299 (2021).

[2]T. L. Makarova, B. Sundqvist, R. Höhne, P. Esquinazi, Y. Kopelevich, P. Scharff, V. A. Davydov, L. S. Kashevarova, A. V. Rakhmanina, Nature 413, 716, (2001) (retracted).

[3]H. Yu, T. Heine, J. Am. Chem. Soc. 145, 19303 (2023).

[4]H. Yu, T. Heine, Sci. Adv. 10 (2024) eadq7954

[5]H. Yu, Y. Jing, T. Heine, Acc. Chem. Res. 58 (2025) 61-72