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Neutron Diffraction Studies of the Molecular Compound [Co2(bta)]n (H4bta =1,2,4,5-Benzenetetracarboxylic Acid): In the Quest of Canted Ferromagnetism
journal contribution
posted on 2013-11-04, 00:00 authored by Oscar Fabelo, Laura Cañadillas-Delgado, Jorge Pasán, Pau Díaz-Gallifa, Catalina Ruiz-Pérez, Francesc Lloret, Miguel Julve, Inés Puente
Orench, Javier Campo, Juan Rodríguez-CarvajalThe exchange mechanism and magnetic
structure of the organic–inorganic layered molecule-based magnet
[Co2(bta)]n (1) (H4bta =1,2,4,5-benzenetetracarboxylic acid) have been
investigated through variable-temperature magnetic susceptibility
measurements and supported with a series of neutron diffraction experiments.
Cryomagnetic studies have shown an antiferromagnetic ordering at a
transition temperature of 16 K that is followed by the appearance
of a weak ferromagnetism below 11 K. The weak antiferromagnetic interlayer
interaction plays an important role in this system in spite of the
long interlayer separation. A ferromagnetic ordering is induced by
applied magnetic fields greater than 1800 G (metamagnetic behavior),
and a slow magnetic relaxation from this ferromagnetic phase to the
antiferromagnetic one is observed. The magnetic structure of 1 has been elucidated at low temperatures in zero field by
neutron powder diffraction measurements and was found to be of antiferromagnetic
nature with the local cobalt(II) spins (magnetic moments) being aligned
ferromagnetically in the ac plane and antiferromagnetically
coupled along the crystallographic b axis. No evidence
for a long-range spontaneous ferromagnetic component below 11 K was
observed in the neutron experiment.