Inelastic neutron scattering and EPR studies of cobalt dimers

The phenomenon of single molecule magnetism has been known for over fifteen years and the fundamentals of this behaviour are well understood; the observed hysteresis is due to an energy barrier for spin reversal, the magnitude of this energy barrier is given by the magnitude and anisotropy of the molecular spin. Despite intensive research it has not been possible to improve the performance of the best single molecule magnets to obtain operating temperatures above a few Kelvin. Recent work has suggested that the anisotropy parameter might play a more important role than previously thought. As such clusters consisting of octahedral Co(II) are promising candidates due to the large anisotropy associated with the spin orbit coupling of the 4T1g ground term. There are however no clear cut cobalt single molecule magnets and the magnetic properties of coordination clusters consisting of octahedral cobalt (II) ions are often complex. Here I present an inelastic neutron scattering study of two cobalt dimers Co2(D2O)(L)4(HL)2(C5D5N)2 and Co2(D2O)L4(HL)4 where L = (CD3)3Co2H [1]. These dimers share a common core; though display different bulk magnetic properties. The dimer was chosen as it is the simplest possible exchange coupled unit that can be studied. The use of inelastic scattering for this problem is incredibly powerful, both due to the zero field nature of the technique and the flexible selection rules [2]. The INS data is presented together with the results of multiple frequency EPR and bulk magnetic properties. The complimentary nature of these techniques allows both the energy scale and the ground state to be determined.

Keywords

Inelastic scattering, Scattering, EPR spectrometers, Cobalt, Dimers, Magnetism, Spin, Magnetic properties

Citation

Mole, R. A., Boeer, A., Simeoni, G., Collison, D., McInnes, E., Timco, G. A. & Winpenny, R. E. P. (2011). Inelastic neutron scattering and EPR studies of cobalt dimers. Paper presented to the Australian and New Zealand Institutes of Physics 35th Annual Condensed Matter and Materials Meeting, Charles Sturt University, Wagga Wagga, NSW, 2nd - 4th February, 2011. Retrieved from: https://physics.org.au/wp-content/uploads/cmm/2011/

URI

https://physics.org.au/wp-content/uploads/cmm/2011/
https://apo.ansto.gov.au/dspace/handle/10238/11913

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