Jahn-teller effects in (3d)2 ions in Al2O3

Theoretical investigations of the spin Hamiltonian parameters and local structures for the tetragonal V3+ and Ti2+ centers in MgO and CaO

“…The fitted F a and F b in Eq. (15) are comparable with those for a-Al 2 O 3 :V 3 þ in the previous studies [29] and can be regarded as suitable. There are several points that may be discussed here.…”

Spin-Spin and Spin-Other-Orbit Interactions of Spin-Hamiltonian Parameters for 3d2(8)Ions in Al2O3Crystals

“…This indicates that the contribution from weaker magnetic interactions are opposite to those from the SO mechanism. For 3d 8 (Ni 2+ and Cu 3+ ) ions, the sum of γ SS , γ SOO and γ SO-SS-SOO for D, ∆g or ∆g ⊥ is positive. This means that if we consider only the SO mechanism, the SH parameters will be overestimated for d 2 ions and underestimated for d 8 ions.…”

“…For 3d 8 (Ni 2+ and Cu 3+ ) ions, the sum of γ SS , γ SOO and γ SO-SS-SOO for D, ∆g or ∆g ⊥ is positive. This means that if we consider only the SO mechanism, the SH parameters will be overestimated for d 2 ions and underestimated for d 8 ions. We find also that the contributions from weaker magnetic interactions to the ZFS parameter D decrease (increase) with increasing charge of impurity ions for 3d 2 (3d 8 ) configurations.…”

“…In past decades, a large number of theoretical and experimental investigations have been reported on the EMR spectra and spin-Hamiltonian parameters of iron group ions in Al 2 O 3 [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. In Al 2 O 3 host crystal, Al 3+ is located at octahedral trigonal symmetry site surrounded by six O 2− ions.…”

“…When transition metal (TM) ions are doped into Al 2 O 3 crystal for replacing Al 3+ ions, impurity defect centers are created. The spin-Hamiltonian (SH) parameters, including the zero field splitting (ZFS) parameter D and g factors (g , g ⊥ ), have been determined for V 3+ and Cr 4+ (3d 2 ) ions in Al 2 O 3 crystals in [8,14,15], whereas for Ni 2+ and Cu 3+ (3d 8 ) ions in [3,17]. The SH parameters of Ni 2+ and Cu 3+ ions in Al 2 O 3 crystals were explained theoretically based on the spin-orbit (SO) mechanism in [1,2].…”