# Magnetically driven loss of centrosymmetry in metallic Pb2CoOsO6

## TL;DR

This paper reports a metallic double-perovskite that undergoes a magnetic phase transition at 45 K, losing its centrosymmetry due to magnetic ordering, which is unusual for metals and opens new avenues for metallic behavior research.

## Contribution

It demonstrates a rare case of magnetic order inducing non-centrosymmetry in a metallic oxide, expanding understanding of symmetry-breaking mechanisms in metals.

## Key findings

- Magnetic transition at 45 K to a non-centrosymmetric state
- Magnetic order relieves frustration in exchange interactions
- Loss of inversion symmetry driven by magnetic ordering

## Abstract

We report magnetic, transport, neutron diffraction, and muon spin rotation data showing that Pb$_2$CoOsO$_6$, 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 LiOsO$_3$, the phase transition in Pb$_2$CoOsO$_6$ is driven by a long-range collinear antiferromagnetic order, with propagation vector $\textbf{k} = (\frac{1}{2},0,\frac{1}{2})$, 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.