Abstract
We analyze magnetic order in Fe chalcogenide , the parent compound of the high-temperature superconductor . Experiments show that magnetic order in this material contains components with momentum and in the Fe only Brillouin zone. The actual spin order depends on the interplay between these two components. Previous works assumed that the ordered state has a single (either or ). In such a state, spins form double stripes along one of the diagonals breaking the rotational symmetry. We show that quantum fluctuations actually select another order—a double plaquette state with equal weight of and components, which preserves symmetry. We argue that the order in is determined by the competition between quantum fluctuations and magnetoelastic coupling.
- Received 9 July 2012
DOI:https://doi.org/10.1103/PhysRevLett.109.157206
© 2012 American Physical Society