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Investigations on the Anisotropic g Factors of the Ni^{3+} Site in La_2Ni_{0.5}Li_{0.5}O_4

100%

Kuang M., Wu S., Zhang Z., Song B.

Acta Physica Polonica A

2013

vol. 123

issue 4

734-736

The anisotropic g factors g_{∥} and g_{⊥} of La_2Ni_{0.5}Li_{0.5}O_4 are theoretically investigated using the perturbation formulae of the g factors for a low spin (S=1/2) 3d^7 ion in tetragonally elongated octahedra. The studied Ni^{3+} (3d^7) center arises from the original Ni^{2+} capturing one hole by Li^{+} doping. The positive anisotropy Δ g (= g_{⊥}-g_{∥}) can be ascribed to the lowest ^2 A_{1g} state due to the obvious (about 0.14 Å) tetragonal elongation of the oxygen octahedron around the Ni^{3+} site via the Jahn-Teller effect, and the effective magnetic moment is also interpreted in a uniform way. The calculated results show good agreement with the experimental data, and the imperfection of the previous studies based on various adjusted tetragonal energy splittings without correlating to the local structure of the magnetic center is thus overcome in this work.

Investigations on the EPR Parameters of KMgF_3:Cr^{+}

88%

Kuang M., Wu S., Hu X., Li G., Zu H.

vol. 125

issue 5

1224-1228

The electron paramagnetic resonance parameters (i.e., g factor, hyperfine structure constant and superhyperfine parameters) of KMgF_3:Cr^{+} are theoretically investigated from the perturbation formulae of these parameters for an octahedral 3 d^5 cluster. As for the calculations of g factor and hyperfine structure constant, both the contributions from the crystal-field and charge transfer mechanisms are included based on the cluster approach. The metal to ligand charge transfer contribution to the g-shift Δg ( ≈ g-2.0023) is the same (negative) in sign and much larger in magnitude as compared to the crystal-field one. The conventional argument that the charge transfer contributions to zero-field splittings are negligible for 3 d^5 ions in fluorides is no longer suitable for Δg analysis of KMgF_3:Cr^{+} due to the dominant second-order charge transfer perturbation term. The charge transfer contribution to hyperfine structure constant exhibits the same sign and about 4% of the crystal-field one. The unpaired spin densities of the fluorine 2s, 2pσ and 2pπ orbitals are quantitatively acquired from the relationships with the relevant molecular orbital coefficients using the uniform model. The present treatments are superior to the previous calculations of directly fitting the experimental superhyperfine parameters.

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2 Acta Physica Polonica A

1 2014

1 2013

2 Kuang M.

2 Wu S.

1 Hu X.

1 Li G.

1 Song B.

1 Zhang Z.

1 Zu H.

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Investigations on the Anisotropic g Factors of the Ni^{3+} Site in La_2Ni_{0.5}Li_{0.5}O_4

Investigations on the EPR Parameters of KMgF_3:Cr^{+}