# Novel Magnetism and Local Symmetry Breaking in a Mott Insulator with Strong Spin Orbit Interactions

## TL;DR

This paper investigates the interplay of strong spin-orbit coupling and electronic correlations in a Mott insulator, revealing a novel canted ferromagnetic phase with local symmetry breaking in Ba₂NaOsO₆.

## Contribution

It provides experimental evidence of local symmetry breaking and a new magnetic phase in a spin-orbit coupled Mott insulator, confirming theoretical predictions.

## Key findings

- Discovery of a canted ferromagnetic phase at low temperatures.
- Observation of local point symmetry breaking prior to magnetic ordering.
- Confirmation of multipolar spin interaction theories.

## Abstract

Study of the combined effects of strong electronic correlations with spin-orbit coupling (SOC) represents a central issue in quantum materials research. Predicting emergent properties represents a huge theoretical problem since the presence of SOC implies that the spin is not a good quantum number. Existing theories propose the emergence of a multitude of exotic quantum phases, distinguishable by either local point symmetry breaking or local spin expectation values, even in materials with simple cubic crystal structure such as Ba$_2$NaOsO$_6$. Experimental tests of such theories by local probes are highly sought for. Here, we report on local measurements designed to concurrently probe spin and orbital/lattice degrees of freedom of Ba$_2$NaOsO$_6$. We find that a novel canted ferromagnetic phase which is preceded by local point symmetry breaking is stabilized at low temperatures, as predicted by quantum theories involving multipolar spin interactions.