Electronic configuration of Mn ions in the π-d molecular ferromagnet β-Mn phthalocyanine studied by soft X-ray magnetic circular dichroism

We have studied the electronic structure of the molecular ferromagnet beta-Mn phthalocyanine (beta-MnPc) in a polycrystalline form, which has been reported to show ferromagnetism at T < 8.6 K, by X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD). From the experimental results and subsequent cluster-model calculation, we find that the ferromagnetic Mn ion in beta-MnPc is largely in the E-4(g) ground state arising from the (e(g))(3)(b(2g))(1) (a(1g))(1) [(d(xz,yz))(3) (d(xy))(1)(d(z2))(1)] configuration of the Mn2+ state. Considering that the highest occupied molecular orbital (HOMO) of MnPc with the E-4(g) ground state originates from the at, orbital of the Mn2+ ion, it is proposed that a(1g)-a(1g) exchange coupling via the it orbitals of the phthalocyanine ring plays a crucial role in the ferromagnetism of beta-MnPc. (C) 2012 Elsevier Ltd. All rights reserved.