Theoretical modelling of exchange interactions in metal-phthalocyanines

ORAL

Abstract

The theoretical understanding of exchange interactions in organics provides a key foundation for quantum molecular magnetism. Recent SQUID magnetometry of a well know organic semiconductor, copper-phthalocyanine [1,2] (CuPc) shows that it forms quasi-one-dimensional spin chains. Green's function perturbation theory calculation [3] is used to find the dominant exchange mechanism. Hybrid density functional theory simulations [4] give a quantitative insight to exchange interactions and electronic structures. Both calculations are performed for different stacking and sliding angles for lithium-Pc, cobalt-Pc, chromium-Pc, and copper-Pc. The exchange interactions depend strongly on stacking angles, but weakly on sliding angles. Our results qualitatively agree with the experiments, and remarkably $\alpha $-cobalt-Pc has a very large exchange above liquid-Nitrogen temperature. Our theoretical predictions on the exchange interactions can guide experimentalists to design novel organic semiconductors. \\[0pt] [1] S. Heutz, et. al., Adv. Mat., 19, 3618 (2007) [2] Hai Wang, et. al., ACS Nano, 4, 3921 (2010) [3] Wei Wu, et. al., Phys. Rev. B 77, 184403 (2008) [4] Wei Wu, et. al., Phys. Rev. B 84, 024427 (2011)

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Authors

  • Wei Wu

    • Department of Materials, Imperial College London

  • Andrew Fisher

    • Department of physics and astronomy, University College London

  • Nic Harrison

    • Department of Chemistry, Imperial College London

  • Michele Serri

    • Department of Materials, Imperial College London

  • Zhenlin Wu

    • Department of Materials, Imperial College London

  • Sandrine Heutz

    • Department of Materials, Imperial College London

  • Tim Jones

    • Department of Chemistry, Warwick University,UK

  • Gabriel Aeppli

    • Department of physics and astronomy, University College London