Strengthening the Magnetic Interactions in Pseudobinary First-Row Transition Metal Thiocyanates, M(NCS)2.
Paddison, Joseph AM
Keyzer, Evan N
da Silva, Ivan
American Chemical Society
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Bassey, E., Paddison, J. A., Keyzer, E. N., Lee, J., Manuel, P., da Silva, I., Dutton, S., et al. (2020). Strengthening the Magnetic Interactions in Pseudobinary First-Row Transition Metal Thiocyanates, M(NCS)2.. Inorganic chemistry, 59 (16), 11627-11639. https://doi.org/10.1021/acs.inorgchem.0c01478
Understanding the effect of chemical composition on the strength of magnetic interactions is key to the design of magnets with high operating temperatures. The magnetic divalent first-row transition metal (TM) thiocyanates are a class of chemically simple layered molecular frameworks. Here, we report two new members of the family, manganese (II) thiocyanate, Mn(NCS)₂, and iron (II) thiocyanate, Fe(NCS)₂. Using magnetic susceptibility measurements on these materials and on cobalt (II) thiocyanate and nickel (II) thiocyanate, Co(NCS)₂ and Ni(NCS)₂, respectively, we identify significantly stronger net antiferromagnetic interactions between the earlier TM ions—a decrease in the Weiss constant, θ, from 29 K for Ni(NCS)₂ to −115 K for Mn(NCS)₂—a consequence of more diffuse 3d orbitals, increased orbital overlap and increasing numbers of unpaired t2g electrons. We elucidate the magnetic structures of these materials: Mn(NCS)₂, Fe(NCS)₂ and Co(NCS)₂ order into the same antiferromagnetic commensurate ground state, whilst Ni(NCS)₂ adopts a ground state structure consisting of ferromagnetically ordered layers stacked antiferromagnetically. We show that significantly stronger exchange interactions can be realised in these thiocyanate frameworks by using earlier TMs.
EPSRC NPIF 2018 fund Laboratory Directed Research and Development Program of Oak Ridge National Laboratory NSERC of Canada PGSD fund Trinity College, Cambridge School of Chemistry, University of Nottingham Hobday Fellowship EPSRC Strategic Equipment Grant EP/M000524/1
External DOI: https://doi.org/10.1021/acs.inorgchem.0c01478
This record's URL: https://www.repository.cam.ac.uk/handle/1810/308075
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