Abstract
We review electronic and magnetic properties of yttrium iron garnets, considered as a superlattice of quantum dots of two different types. Those are the tetrahedral and octahedral iron-oxygen clusters characterized by their respective localized energy levels with the orbital eigenstates, specified by the clusters’ respective point symmetries. We discuss two-dot mechanisms of the superexchange coupling between spins, attached to the orbital states, via the tunneling, only (between clusters of different types), or via the tunneling combined with the next-nearest neighbor hopping (between clusters of the same type). The electronic density of states of a superlattice of the clusters is found and analyzed both for pure and valence-uncompensated garnet systems. A scheme of control of the superexchange coupling due to an external magnetic field, applied to the system is proposed.
6 More- Received 22 December 2003
DOI:https://doi.org/10.1103/PhysRevB.69.214434
©2004 American Physical Society