Spin Wave Theory of Double Exchange Magnets

TL;DR

This paper investigates the spin wave spectrum of half-metallic double exchange magnets with superexchange coupling, revealing that the competition between interactions does not favor canted spin states under typical conditions.

Contribution

It provides a detailed spin-wave analysis including quantum corrections for double exchange magnets with superexchange, highlighting the stability of ferromagnetic order.

Findings

Quantum corrections to spin wave spectrum are calculated.

Double exchange and superexchange competition does not stabilize canted states.

The ferromagnetic phase remains stable under typical magnetic fields.

Abstract

An isotropic half-metallic double exchange magnet with a direct superexchange coupling between the localized spins is studied within the spin-wave (1/S) expansion. The momentum dependence of the spin wave spectrum (including quantum corrections) in the ferromagnetic phase at T=0 is investigated. Based on the calculated spin wave spectrum of the canted state, it is shown that as long as the external magnetic field is not too strong, the double exchange -- superexchange competition does not result in a stabilization of a two-sublattice canted spin ordering.