Quantifying magnetic anisotropy using X-ray and neutron diffraction

IUCrJ

Jacob Overgaard¹  Emil Andreasen Klahn¹  Emil Damgaard-Møller¹  Lennard Krause¹  Abinash Swain²  Maheswaran Shanmugam²  Shalini Tripathi²  Arsen Gukasov³  Iurii Kibalin³ 

[1] Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus C 8000, Denmark;Department of Chemistry, IIT Bombay, Powai, Mumbai, Maharashtra 400076, India;LLB, CEA, CE de Saclay, Gif sur Yvette 91191, France;

关键词: magnetic anisotropy;    single-molecule magnets;    synchrotron diffraction;    polarized neutron diffraction;    charge, spin and momentum densities;    materials science;    magnetic structures;   

DOI  :  10.1107/S2052252521008290

来源: DOAJ

【 摘 要 】

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 d_{x^2 - y^2}. 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.

【 授权许可】

Unknown