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arXiv · 1701.06485

Time-reversal symmetry breaking hidden order in Sr$_2$(Ir,Rh)O$_4$

Jaehong Jeong·Yvan Sidis·Alex Louat·Véronique Brouet·Philippe Bourges
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Abstract

Layered 5$d$ transition iridium oxides, Sr$_2$(Ir,Rh)O$_4$, are described as unconventional Mott insulators with strong spin-orbit coupling. The undoped compound, Sr$_2$IrO$_4$, 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$_2$(Ir,Rh)O$_4$, 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.

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Jaehong Jeong, Yvan Sidis, Alex Louat, Véronique Brouet, Philippe Bourges. 2017-01-23. Time-reversal symmetry breaking hidden order in Sr$_2$(Ir,Rh)O$_4$. https://doi.org/10.1038/ncomms15119

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