Phase Diagram of Ba$_{2}$NaOsO$_{6}$, a Mott insulator with strong spin orbit interactions

TL;DR

This study uses $^{23}$Na NMR to explore the phase diagram of Ba$_{2}$NaOsO$_{6}$, revealing a canted ferromagnetic phase and local symmetry breaking influenced by magnetic field strength.

Contribution

It provides detailed NMR evidence of magnetic and structural phases in Ba$_{2}$NaOsO$_{6}$ under high magnetic fields, extending previous low-field studies.

Findings

Identification of a canted ferromagnetic phase

Detection of local point symmetry breaking

Phase diagram showing wider symmetry-breaking region at higher fields

Abstract

We report $^{23}$Na nuclear magnetic resonance (NMR) measurements of the Mott insulator with strong spin-orbit interaction Ba$_{2}$NaOsO$_{6}$ as a function of temperature in different magnetic fields ranging from 7 T to 29 T. The measurements, intended to concurrently probe spin and orbital/lattice degrees of freedom, are an extension of our work at lower fields reported in Nat. Commun., v 8, 14407 (2017). We have identified clear quantitative NMR signatures that display the appearance of a canted ferromagnetic phase, which is preceded by local point symmetry breaking. We have compiled the field temperature phase diagram extending up to 29 T. We find that the broken local point symmetry phase extends over a wider temperature range as magnetic field increases.