Issue 6, 2018

Probing the origin of the giant magnetic anisotropy in trigonal bipyramidal Ni(ii) under high pressure


Understanding and controlling magnetic anisotropy at the level of a single metal ion is vital if the miniaturisation of data storage is to continue to evolve into transformative technologies. Magnetic anisotropy is essential for a molecule-based magnetic memory as it pins the magnetic moment of a metal ion along the easy axis. Devices will require deposition of magnetic molecules on surfaces, where changes in molecular structure can significantly alter magnetic properties. Furthermore, if we are to use coordination complexes with high magnetic anisotropy as building blocks for larger systems we need to know how magnetic anisotropy is affected by structural distortions. Here we study a trigonal bipyramidal nickel(II) complex where a giant magnetic anisotropy of several hundred wavenumbers can be engineered. By using high pressure, we show how the magnetic anisotropy is strongly influenced by small structural distortions. Using a combination of high pressure X-ray diffraction, ab initio methods and high pressure magnetic measurements, we find that hydrostatic pressure lowers both the trigonal symmetry and axial anisotropy, while increasing the rhombic anisotropy. The ligand–metal–ligand angles in the equatorial plane are found to play a crucial role in tuning the energy separation between the dx2y2 and dxy orbitals, which is the determining factor that controls the magnitude of the axial anisotropy. These results demonstrate that the combination of high pressure techniques with ab initio studies is a powerful tool that gives a unique insight into the design of systems that show giant magnetic anisotropy.

Graphical abstract: Probing the origin of the giant magnetic anisotropy in trigonal bipyramidal Ni(ii) under high pressure

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Article information

Article type
Edge Article
15 Oct 2017
18 Dec 2017
First published
19 Dec 2017
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2018,9, 1551-1559

Probing the origin of the giant magnetic anisotropy in trigonal bipyramidal Ni(II) under high pressure

G. A. Craig, A. Sarkar, C. H. Woodall, M. A. Hay, K. E. R. Marriott, K. V. Kamenev, S. A. Moggach, E. K. Brechin, S. Parsons, G. Rajaraman and M. Murrie, Chem. Sci., 2018, 9, 1551 DOI: 10.1039/C7SC04460G

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