A space-symmetry approach to the p-d hybridization and direct p-p hopping in yttrium-iron garnets

Abstract

The first thorough symmetry analysis of the p-d hybridization and p-p hopping is performed for yttrium-iron garnets. Group-theoretical calculations of spin-independent p-d hybridization and p-p transfer-matrix elements allow us to determine symmetry-adapted `channels' in the crystal unit cell. The results clearly indicate what role is played by each of the interactions in a possible charge transportation. The p-d hybridization turns out to be restricted to the small-sized octahedral and tetrahedral clusters of iron-oxygen neighbours; which results from the specific complex geometry of garnets. A propagation between the hybridizing clusters of the same type is realized by the p-p hopping to the second neighbours. The p-p hopping itself is shown to be restricted to small-sized oxygen clusters. Moreover, the second-neighbour p-p hopping between octahedral hybridizing clusters shows a strong anisotropy along the ⟨111⟩ axis. The p-p hopping between the nearest neighbours appears less important. An inter-sublattice charge motion may be mediated solely by the p-d hybridization since the nearest-neighbour hybridizing clusters share a common oxygen.

Investigating the role of diamagnetic Cd2+ ions on the structural, optical, and magnetic properties of YIG

“…When studying the magnetic properties of bismuth-doped YIG, Geller et al [29] and Euler et al [30] came across the hybridization of Bi 6p in Fe 3d orbital-overlap occurring in iron ion at (d) site, explaining the increase in the super-exchange interaction, and increasing M s . Similar reasons may be behind the increase of M s observed in the 0.08 sample, where there is a chance that hybridization of the 4d closed shell in the Fe 3d orbital-overlap occurred with the substitution of Y 3+ ions with Cd 2+ ions, overweighing the effect of the geometrical deformation in this sample and causing an overall increase of M s [31].…”