Non-Degenerate Ground State in the Antiferromagnetic Double-Exchange Model on a Triangular Lattice

摘要

In order to study effects of frustration in an itinerant electron system, weinvestigate ground states of the antiferromagnetic double-exchange model on atriangular lattice. In this model, pseudo-spins are coupled to electrontransfer integrals in such a way that antiparallel configurations ofpseudo-spins gain kinetic energies. Although the antiferromagnetic Ising modelon a triangular lattice shows macroscopic dengenerate ground states, thepresent model shows that the degeneracy is lifted due to long-range natures ofthe double exchange interactions. Spin ordering at the ground state is alsodiscussed.