Heisenberg model with Dzyaloshinskii-Moriya interaction: A Schwinger boson study
Abstract
We present a Schwinger-boson approach to the Heisenberg model with Dzyaloshinskii-Moriya interaction. We write the anisotropic interactions in terms of Schwinger bosons keeping the correct symmetries present in the spin representation, which allows us to perform a conserving mean-field approximation. Unlike previous studies of this model by linear spin-wave theory, our approach takes into account magnon-magnon interactions and includes the effects of three-boson terms characteristic of noncollinear phases. The results reproduce the linear spin-wave predictions in the semiclassical large-S limit, and show a small renormalization in the strong quantum limit S=1/2. For the sake of definiteness, we specialize the calculations for the pattern of Moriya vectors corresponding to the orthorhombic phase in La_2CuO_4, and give a fairly detailed account of the behavior of ground-state energy, anisotropy gap, and net ferromagnetic moment. In the last part of this work we generalize our approach to describe the geometry of the intermediate phase in La_{2-x}Nd_xCuO_4, and discuss the effects of including nondegenerate 2p_z oxygen orbitals in the calculations.
Keywords
Cite
@article{arxiv.cond-mat/9611116,
title = {Heisenberg model with Dzyaloshinskii-Moriya interaction: A Schwinger boson study},
author = {L. O. Manuel and C. J. Gazza and A. E. Trumper and H. A. Ceccatto},
journal= {arXiv preprint arXiv:cond-mat/9611116},
year = {2009}
}
Comments
9 text pages, Latex, 10 figures included as eps files, to appear in Phys. Rev. B