We report magnetic, transport, neutron diffraction, and muon spin rotation data showing that Pb2CoOsO6, a newly synthesized metallic double-perovskite with a centrosymmetric space group at room temperature, exhibits a continuous second-order phase transition at 45 K to a magnetically ordered state with a non-centrosymmetric space group. The absence of inversion symmetry is very uncommon in metals, particularly metallic oxides. In contrast to the recently reported ferroelectric-like structural transition in LiOsO3, the phase transition in Pb2CoOsO6 is driven by a long-range collinear antiferromagnetic order, with propagation vector k=(21,0,21), which relieves the frustration associated with the symmetry of themagnetic exchanges. This magnetically-driven loss of inversion symmetry represents a new frontier in the search for novel metallic behavior.
@article{arxiv.1902.04482,
title = {Magnetically driven loss of centrosymmetry in metallic Pb2CoOsO6},
author = {A. J. Princep and H. L. Feng and Y. F. Guo and F. Lang and H. M. Weng and P. Manuel and D. Khalyavin and A. Shenshyn and M. Rahn and Y. H. Yuan and Y. Matsushita and S. J. Blundell and K. Yamaura and A. T. Boothroyd},
journal= {arXiv preprint arXiv:1902.04482},
year = {2020}
}