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Magnetoelectric Coupling on the Fused Azulene Oligomers

submitted on 01.04.2021, 02:26 and posted on 01.04.2021, 13:26 by Alexandra Valentim, Daniel J. Garcia, João A. Plascak

The global magnetic phase diagram for fused azulene oligomers is obtained by using a fermionic Hubbard Hamiltonian, a intermediate model between the molecular (Pariser-Parr-Pople empiric Hamiltonian) and spin-1/2 antiferromagnetic Heisenberg approaches. As a function of the on-site coulomb repulsion and the oligomer size we show that fused azulene transitions from a singlet (S = 0) to a higher-spin (S = 1, 2, 3) ground state. Near the quantum magnetic phase transition the electric dipole moment, present on fused azulene molecules, couples with the magnetic moment leading to a divergent magnetoelectric susceptibility at the boundary lines of the magnetic phase diagram. These spontaneous electric and magnetic polarizations, together with the magnetoelectric coupling between them, indicate that fuzed azulene molecules are potentially strong candidates for purely organic multiferroic materials.


This work has been supported by the Argentinian agency CONICET, PICT 2012/1069 (AV and DJG) and by the Brazilian agencies FAPEMIG, CAPES and CNPq through grants numbers 403825/2014-8 and153199/2018- 0 (AV), 400484/2016-1 and 302504/2017-6 (JAP).


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Universidade Federal de Mato Grosso



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Declaration of Conflict of Interest

The authors have no conflicts of interest to declare. All co-authors have seen and agree with the contents of the manuscript and there is no financial interest to report.