Abstract
We formulate and study an effective Hamiltonian for low-energy Kramers doublets of ions on a square lattice. We find that the system exhibits a magnetically hidden order in which the expectation values of the local spin and orbital moments both vanish. The order parameter responsible for a time-reversal symmetry breaking has a composite nature and is a spin-orbital analog of a magnetic octupole. We argue that such a hidden order is realized in the layered perovskite .
- Received 10 June 2009
DOI:https://doi.org/10.1103/PhysRevLett.103.067205
©2009 American Physical Society