X-ray magnetic circular dichroism ͑XMCD͒ measured at T = 6 K and 0 H = 5 T on the ␣-phase Fephthalocyanine ͑FePc͒ textured thin films shows that the Fe 2+ ions present an unusually large, highly unquenched m L = 0.53Ϯ 0.04 B orbital component, with planar anisotropy. The spin m S = 0.64Ϯ 0.05 B and the intra-atomic magnetic dipolar m T components were also obtained. The m L / m S = 0.83 ratio is the largest measured in 3d complexes and compounds. The origin of this unusually high orbital moment is the incompletely filled e g level lying close to the Fermi energy. This explains the unusually large and positive hyperfine field detected by Mössbauer spectroscopy in FePc. The FePc film strong planar anisotropy inferred from XMCD experiments is fully confirmed by magnetization measurements.
We report on the magnetic properties of the supra-molecular compound iron(II) phthalocyanine in its α-form. dc-and ac-susceptometry measurements and Mössbauer experiments show that the iron atoms are strongly magnetically coupled into ferromagnetic Ising chains with very weak antiferromagnetic interchain coupling. The transition to 3D magnetic ordering below 10 K is hindered by the presence of impurities or other defects, by which the domain-wall arrangements along individual chains become gradually blocked/frozen, leading to a disordered 3D distribution of ferromagnetic chain segments. Below 5 K, field-cooled and zero-field-cooled magnetization measurements show strong irreversible behavior, attributed to pinning of the domain-walls by the randomly distributed defects in combination with the interchain coupling. High-field magnetization experiments reveal a canted arrangement of the moments in adjacent ferromagnetic chains.
The tridecanuclear heterovalent mixed-metal (Mn11Gd2) complex [MnIII
9MnII
2GdIII
2(O)8(OH)2(O2CR)17(NO3)2(H2O)] has been obtained from the reaction of the hexanuclear compound [Mn6O2(Piv)10(4-Me-py)2.5(PivH)1.5] with Gd(NO3)3·6H2O in CH3CN. The complex presents an unusual “bell”-shaped core with a high-spin ground state and is a new member of the high-nuclearity 3d-4f single-molecule magnets family.
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