Layered 5d transition iridium oxides, Sr2(Ir,Rh)O4, are described as unconventional Mott insulators with strong spin-orbit coupling. The undoped compound, Sr2IrO4, 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 Sr2(Ir,Rh)O4, distinct from the usual antiferromagnetic pseudo-spin 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.
@article{arxiv.1701.06485,
title = {Time-reversal symmetry breaking hidden order in Sr$_2$(Ir,Rh)O$_4$},
author = {Jaehong Jeong and Yvan Sidis and Alex Louat and Véronique Brouet and Philippe Bourges},
journal= {arXiv preprint arXiv:1701.06485},
year = {2017}
}
Comments
7 figures: 3 in main text and 4 in the supplementary materials