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Magnetic response of an iron phthalocyanine lattice on Au(111)
Naoka Ohta, Noriyuki Tsukahara, Noriaki Takagi and Maki Kawai
Department of Advanced Materials Science, Graduate School of Frontier Sciences, the University of Tokyo, Kashiwa, Chiba 277-8561 Japan
We investigated electronic structure of an iron phthalocyanine (FePc) lattice on Au(111) under magnetic fields by using scanning tunneling microscopy and spectroscopy (STM/STS). At low coverage, FePc molecules adsorb on Au(111) surface isolated from each other. Isolated FePc molecules show Kondo resonance in STS spectra [1,2]. When the coverage increases, FePc molecules self-assemble into a two dimensional lattice. Upon the formation of the molecular lattice, the STS spectral shape changes [2]. In this study, we tried to reveal the origin of the spectral change. The spectral evolution under magnetic field was anisotropic. Furthermore, adjacent molecules showed different spectral evolution. We attribute the behavior to the formation of Ising type antiferromagnetic order between molecular spins.
[1] N. Tsukahara, S. Shiraki, S. Itou, N. Ohta, N. Takagi and M. Kawai, Phys. Rev. Lett. 106, 187201 (2011).
[2] E. Minamitani, N. Tsukahara, D. Matsunaka, Y. Kim, N. Takagi and M. Kawai, Phys. Rev. Lett. 109, 086602 (2012).