Detecting an Eight Magnetic Pole State using Chiral Phonons

The idea that magnetism doesn’t necessarily always have a dipolar configuration is not a new one, but it’s not an easy theory to find evidence for. Most recently a team …. Detecting an Eight Magnetic Pole State using Chiral Phonons.

Most recently a team of scientists at the University of Toronto used a new method involving vibrational energy in the form of phonons to find evidence for an octupolar magnetic order. In the associated paper in Physical Review Letters (paywalled, arXiv version) by [Ruairidh Sutcliffe] et al. We can find more details on this method and what their findings may mean for various fields.

Naturally, this is a quantum-level phenomenon that requires Raman spectroscopy to be detectable via said phonons. The materials investigated here are also somewhat exotic, ranging from actinides like NpO 2 to transition metal oxides like Sr 2 MgReO 6, while having on common strong spin-orbit coupling. Where the phonons come into play is that they can be used to indirectly measure crystal lattice distortions due to the pseudo-angular momentum assigned to the phonons.

This generates pseudo-chiral phonons which then show up in the Raman spectroscopy.