Modelling spin Hamiltonian parameters of molecular nanomagnets

Abstract

Molecular nanomagnets encompass a wide range of coordination complexes possessing several potential applications. A formidable challenge in realizing these potential applications lies in controlling the magnetic properties of these clusters. Microscopic spin Hamiltonian (SH) parameters describe the magnetic properties of these clusters, and viable ways to control these SH parameters are highly desirable. Computational tools play a proactive role in this area, where SH parameters such as isotropic exchange interaction (J), anisotropic exchange interaction (Jx, Jy, Jz), double exchange interaction (B), zero-field splitting parameters (D, E) and g-tensors can be computed reliably using X-ray structures. In this feature article, we have attempted to provide a holistic view of the modelling of these SH parameters of molecular magnets. The determination of J includes various class of molecules, from di- and polynuclear Mn complexes to the {3d-Gd}, {Gd-Gd} and {Gd-2p} class of complexes. The estimation of anisotropic exchange coupling includes the exchange between an isotropic metal ion and an orbitally degenerate 3d/4d/5d metal ion. The double-exchange section contains some illustrative examples of mixed valance systems, and the section on the estimation of zfs parameters covers some mononuclear transition metal complexes possessing very large axial zfs parameters. The section on the computation of g-anisotropy exclusively covers studies on mononuclear Dy(III) and Er(III) single-ion magnets. The examples depicted in this article clearly illustrate that computational tools not only aid in interpreting and rationalizing the observed magnetic properties but possess the potential to predict new generation MNMs.

Investigation of the magnetic anisotropy in a series of trigonal bipyramidal Mn(ii) complexes

“…The g values of these three complexes are totally isotropic in nature, 2.00, as the g value depends only on the ground electronic state. The sign of D SOC here cannot be rationalized using the M L value of the d-orbitals and their excitation, as has been routinely done in other cases, 35 as here the contributions arise solely due to spin-flip transitions. 36 Despite the significant structural variations observed, the magnitude of the computed D values is nearly the same in all three complexes.…”

Magnetic excitations in molecular magnets with complex bridges: the tetrahedral molecule Ni4Mo12

“…Moreover, one can distinguish the eigenvalues of tetramer Hamiltonian corresponding to m = 0 and m = 0, with S zz (q, ω n n ) = 0 and S xx (q, ω n n ) = 0, S yy (q, ω n n ) = 0, respectively. This affects directly the integrated intensities, such that choosing r 12 = (0, 0, r z ) and r 34 = (r x , 0, 0) from (2.1) yields I 10 ∝ γ 10…”

“…The physical properties, such as energy spectra, susceptibility, etc., of magnetic clusters at the nanoscale depend on their size, shape and the presence of different bondings among the constituent chemical elements and thus the distribution of ligands between the magnetic ions (for more details see [1][2][3][4] and references therein). Some prominent examples are Mn based magnetic compounds [5][6][7][8][9][10][11] and spin clusters with Ni magnetic ions [12][13][14][15] .…”

“…Here, the present method will be validated by reproducing the experimentally obtained INS spectrum of a molecular magnet that has generated a great deal of interest among researchers both on the theoretical, as well as the experimental sides. This is the magnetic molecule [Mo 12 O 30 (µ 2 -OH) 10 30 . We would like to point out that previous studies 31,32 did not succeed to obtain the main peaks and the broadening in the INS spectrum, see FIG.…”

Fabrication of TiO2 Nanoscale Thin Film and Its Structural Properties

“…According to the prediction of previous studies [7], fractures are clearly visible. Many fractures can be seen in the samples due to that stress during the drying time or the annealing process.…”