Magnetism in All-Carbon Structures with Negative Gaussian Curvature

Noejung Park⁽¹⁾, Jisoon Ihm⁽¹⁾, Eiji Osawa⁽²⁾, Mina Yoon⁽³⁾, Savas Berber⁽³⁾, and David Tomanek⁽³⁾

(1) School of Physics, Seoul Nantional University, Korea

(2) NanoCarbon Research Institute Limited, Japan

(3) Department of Physics and Astronomy, Michigan State University, USA

We apply the ab initio spin density functional theory to study magnetism in all-carbon nanostructures. It is observed that particular systems, which are associated with schwarzite and contain no under-coordinated carbon atoms, carry a net magnetic moment in the ground state. We postulate that in this and other non-alternant aromatic systems with negative Gaussian curvature, unpaired spins can be introduced by sterically protected carbon radicals.

Reference
[1] Noejung Park et al., Phys. Rev. Lett., 91, 237204 (2003).

[Figure 1] (a) The model system of a carbon tetrapod, the building block of schwarzite. The four extremites consists of (9,0) carbon nanotubes with the zigzag edges. (b) trivalent carbon radicals emphasized by the gray spheres in the aromatic system of the otherwise tetravalent carbon atoms in the tetrapod core. (c) sp2- and (d)sp3 terminated (9,0) nanotube with hydrogen atoms.

[Figure 2] Spin-resolved electronic density of states of model systems