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Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/jspui/handle/10054/4538

Title: Magnetic properties and spin dynamics in the single-molecule paramagnets Cu(6)Fe and Cu(6)Co
Authors: KHUNTIA, P
MARIANI, M
MOZZATI, MC
SORACE, L
ORSINI, F
LASCIALFARI, A
BORSA, F
MAXIM, C
ANDRUH, M
Keywords: relaxation
complexes
fe
cr
Issue Date: 2009
Publisher: AMER PHYSICAL SOC
Citation: PHYSICAL REVIEW B, 80(9), -
Abstract: The magnetic properties and the spin dynamics of two molecular magnets have been investigated by magnetization and dc susceptibility measurements, electron paramagnetic resonance and proton nuclear magnetic resonance (NMR) over a wide range of temperatures (1.6-300K) at applied magnetic fields H=0.5 and 1.5 T. The two molecular magnets consist of Cu(II)(saldmen)(H(2)O)}(6){Fe(III)(CN)(6)}](ClO(4))(3)center dot 8H(2)O in short Cu(6)Fe (here H saldmen is the Schiff base resulted by reacting salicylaldehyde with N,N-dimethylethylenediamine) and the analog compound with cobalt, Cu(6)Co. It is found that in Cu(6)Fe, whose magnetic core is constituted by six Cu(2+) ions and one Fe(3+) ion all with s=1/2, a weak ferromagnetic interaction between Cu(2+) moments through the central Fe(3+) ion with J=0.14 K is present, while in Cu(6)Co the Co(3+) ion is diamagnetic and the weak interaction is antiferromagnetic with J=-1.12 K. The NMR spectra show the presence of nonequivalent groups of protons with a measurable contact hyperfine interaction consistent with a small admixture of s wave function with the d function of the magnetic ion. The NMR relaxation results are explained in terms of a single-ion (Cu(2+), Fe(3+), Co(3+)) uncorrelated spin dynamics with an almost temperature-independent correlation time due to the weak magnetic exchange interaction. We conclude that the two molecular magnets studied here behave as single-molecule paramagnets with a very weak intramolecular interaction, almost on the order of the dipolar intermolecular interaction. Thus they represent a separate class of molecular magnets which differ from the single-molecule magnets investigated up to now, where the intramolecular interaction is much larger than the intermolecular one.
URI: http://dx.doi.org/10.1103/PhysRevB.80.094413
http://dspace.library.iitb.ac.in/xmlui/handle/10054/4538
http://hdl.handle.net/10054/4538
ISSN: 1098-0121
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