Sanyal, Sambuddha ; Banerjee, Argha ; Damle, Kedar ; Sandvik, Anders W.
(2012)
*Antiferromagnetic order in systems with doublet S _{tot}=1/2 ground states*
Physical Review B: Condensed Matter and Materials Physics, 86
(6).
Article ID 064418.
ISSN 2469-9950

Full text not available from this repository.

Official URL: http://journals.aps.org/prb/abstract/10.1103/PhysR...

Related URL: http://dx.doi.org/10.1103/PhysRevB.86.064418

## Abstract

We use projector quantum Monte Carlo methods to study the doublet ground states of two-dimensional S=1/2 antiferromagnets on L×L square lattices with L odd. We compute the ground-state spin texture Φ^{z}(⃗r)=⟨S^{z}(⃗r)⟩↑ in the ground state |G⟩↑ with S^{z}_{tot}=1/2, and relate n^{z}, the thermodynamic limit of the staggered component of Φ^{z}(⃗r), to m, the thermodynamic limit of the magnitude of the staggered magnetization vector in the singlet ground state of the same system with L even. If the direction of the staggered magnetization in |G⟩↑ were fully pinned along the ˆz axis in the thermodynamic limit, then we would expect n^{z}/m=1. By studying several different deformations of the square lattice Heisenberg antiferromagnet, we find instead that n^{z}/m is a universal function of m, independent of the microscopic details of the Hamiltonian, and well approximated by n^{z}/m≈0.266+0.288m−0.306m^{2} for S=1/2 antiferromagnets. We define n^{z} and m analogously for spin-S antiferromagnets, and explore this universal relationship using spin-wave theory, a simple mean-field theory written in terms of the total spin of each sublattice, and a rotor model for the dynamics of the staggered magnetization vector. We find that spin-wave theory predicts n^{z}/m≈(0.987−1.003/S)+0.013m/S to leading order in 1/S, while the sublattice-spin mean-field theory and the rotor model both give n^{z}/m=S/(S+1) for spin-S antiferromagnets. We argue that this latter relationship becomes asymptotically exact in the limit of infinitely long-range unfrustrated exchange interactions.

Item Type: | Article |
---|---|

Source: | Copyright of this article belongs to American Physical Society. |

ID Code: | 103817 |

Deposited On: | 09 Mar 2018 11:30 |

Last Modified: | 09 Mar 2018 11:30 |

Repository Staff Only: item control page