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Quantifying magnetic anisotropy using X-ray and neutron diffraction

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  • Emil Andreasen Klahn
  • ,
  • Emil Damgaard-Møller
  • ,
  • Lennard Krause
  • Iurii Kibalin, CEA Saclay, France
  • Arsen Gukasov, CEA Saclay, France
  • Shalini Tripathi, Indian Institute of Technology, Bombay, India
  • Abinash Swain, Indian Institute of Technology, Bombay, India
  • Maheswaran Shanmugam, Indian Institute of Technology, Bombay, India
  • Jacob Overgaard

In this work, the magnetic anisotropy in two iso-structural distorted tetrahedral Co(II) complexes, CoX 2tmtu2 [X = Cl(1) and Br(2), tmtu = tetramethylthiourea] is investigated, using a combination of polarized neutron diffraction (PND), very low-temperature high-resolution synchrotron X-ray diffraction and CASSCF/NEVPT2 ab initio calculations. Here, it was found consistently among all methods that the compounds have an easy axis of magnetization pointing nearly along the bisector of the compression angle, with minute deviations between PND and theory. Importantly, this work represents the first derivation of the atomic susceptibility tensor based on powder PND for a single-molecule magnet and the comparison thereof with ab initio calculations and high-resolution X-ray diffraction. Theoretical ab initio ligand field theory (AILFT) analysis finds the d xy orbital to be stabilized relative to the d xz and d yz orbitals, thus providing the intuitive explanation for the presence of a negative zero-field splitting parameter, D, from coupling and thus mixing of d xy and . Experimental d-orbital populations support this interpretation, showing in addition that the metal-ligand covalency is larger for Br-ligated 2 than for Cl-ligated 1.

Original languageEnglish
Pages (from-to)833-841
Number of pages9
Publication statusPublished - Sep 2021

    Research areas

  • charge, spin and momentum densities, magnetic anisotropy, magnetic structures, materials science, polarized neutron diffraction, single-molecule magnets, synchrotron diffraction

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