2D material offers novel spin state for spintonics

Students of spintronics have another spin state to add to their tool box: a 2D material hosting a ‘spiral spin liquid’ – in which magnetic spins form fluctuating corkscrew-like structures.

In this case, the material is the van der Waals honeycomb magnet iron trichloride, which has a layer of iron atoms sandwiched between two layers of chlorine atoms, and can stack into 3D blocks.

US lab Oak Ridge National Laboratory grew the host material and finally demonstrated this long-predicted behaviour.

“Our study shows that the concept of a spiral spin liquid is viable for the broad class of honeycomb lattice materials,” said ORNL researcher Andrew Christianson. “It gives the community a new route to explore spin textures and novel excitations, such as fractons, that then may be used in future applications, such as quantum computing.” – Fractons are collective quantised vibrations.

Neutron scattering was used to probe the system, according to ORNL, and is a promising platform to further study fracton physics in spiral spin liquids. It allows the energy and momentum exchanged between neutrons and a sample to be measured, allowing the magnetic properties to be inferred.

And what is the magnetic structure of a spiral spin liquid?

“It looks like a topographic map of a group of mountains with a bunch of rings going outward,” said fellow scientist Matthew Stone. “If you were to walk along a ring, all spins would point in the same direction. But if you walk outward and cross different rings, you’re going to see those spins begin to rotate about their axes. That’s the spiral.”

The work is published in Physical Review Letters as ‘Spiral spin liquid on a honeycomb lattice‘ – abstract available without payment.