Crystal field theory and electric field gradients at 49Ti nuclei sites in LaTiO3

Even and odd crystal fields on Fe2+ ions, local lattice distortion parameters, electron-deformation interaction, and magnetoelectric coupling in FeCr2O4

“…The second term describes the electrostatic potential created by the electronic distribution of the 2s and 2p oxygen shells. Numerical values of p k and γ k for the O 2+ ion are given in [25].…”

“…For brevity (11), the indices α = α i + α j , ξ = γ + α, γ = γ k are omitted. The difference between (11) and the expressions from [25] is that we employed the factor (x 2 α + γ) instead of the factor (x 2 α − γ) used in [25]. Calculation by formulas (11) using the Hartree-Fock wave functions of iron and oxygen ions [26] gives the following results: a (2) kl −9277 cm −1 , a (4) kl −3880 cm −1 .…”

Theory of magnetic resonance as an orbital state probe

“…12,13 Actually, different pieces of the above results were obtained earlier by several authors. 5,6,[18][19][20][21][22]24,25,33,36 Orbital structure, superexchange interactions, and magnetic ground state are reproduced here to illustrate the realistic model with reasonable parameters, and, what is more important, to uncover particular mechanisms of titanates orbital and magnetic ground states formation that has not been done before.…”

“…This admixture is not very big in real compounds because of large crystal-field splitting of the Ti 3+ 3d-t 2g levels in both of them. The central point of the discussion of titanates [2][3][4][5][6][7][8]12,13,[15][16][17][18][19][20][21][22][23][24][25]33,36,[42][43][44] is the question of what approach is more relevant as a starting point for these compounds description: "crystal-field" approach, when it is assumed that the crystal field is much stronger than superexchange interaction, H cf ӷ H ex ; or the "orbital fluctuations" approach, when the opposite relation ͑H cf Ӷ H ex ͒ is considered. From this point of view the present work is an investigation and a comparison of two models on the example of titanates rather than a study of some real compound properties.…”

Interplay between crystal-field splitting and superexchange interaction in thet2gorbital Mott insulator

“…In the alternative framework, [19][20][21][22][23][24][25][26][27][28][29][30][31][32] the LCF caused by the lattice distortions controls the orbitals at a TM site instead of the SE. For the states with the t 2g symmetry the interaction with the GdFeO 3 -type intrinsic perovskite deformation (GFOD), trigged by ionic size mismatch effects, is crucial.…”