Quantifying magnetic anisotropy using X-ray and neutron diffraction

3 years ago

Quantifying magnetic anisotropy using X-ray and neutron diffraction

$Quantifying magnetic anisotropy using X-ray and neutron diffraction$

Emil Andreasen Klahn, Emil Damgaard-Møller, Lennard Krause, Iurii Kibalin, Arsen Gukasov, Shalini Tripathi, Abinash Swain, Maheswaran Shanmugam, Jacob Overgaard

In this work, the magnetic anisotropy in two iso-structural distorted tetrahedral Co(II) complexes, CoX2tmtu2 [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 dxy orbital to be stabilized relative to the dxz and dyz orbitals, thus providing the intuitive explanation for the presence of a negative zero-field splitting parameter, D, from coupling and thus mixing of dxy and dx2 − y2. 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.

Publisher URL: http://scripts.iucr.org/cgi-bin/paper

Open URL: https://journals.iucr.org/m/issues/2021/05/00/lt5038/lt5038.pdf

DOI: 10.1107/S2052252521008290