Time-reversal symmetry breaking hidden order in Sr<sub>2</sub>(Ir,Rh)O<sub>4</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28436436.
- Also identified by DOI 10.1038/ncomms15119 and PMC identifier 5413971.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Layered 5d transition iridium oxides, Sr<sub>2</sub>(Ir,Rh)O<sub>4</sub>, are described as unconventional Mott insulators with strong spin-orbit coupling. The undoped compound, Sr<sub>2</sub>IrO<sub>4</sub>, is a nearly ideal two-dimensional pseudospin-1/2 Heisenberg antiferromagnet, similarly to the insulating parent compound of high-temperature superconducting copper oxides. Using polarized neutron diffraction, we here report a hidden magnetic order in pure and doped Sr<sub>2</sub>(Ir,Rh)O<sub>4</sub>, distinct from the usual antiferromagnetic pseudospin ordering. We find that time-reversal symmetry is broken while the lattice translation invariance is preserved in the hidden order phase. The onset temperature matches that of the odd-parity hidden order recently highlighted using optical second-harmonic generation experiments. The novel magnetic order and broken symmetries can be explained by the loop-current model, previously predicted for the copper oxide superconductors.