"We have detected the existence of a fundamentally new state of matter that can be regarded as a quantum analogue of a liquid crystal," says assistant professor David Hsieh. "There are numerous classes of such quantum liquid crystals that can, in principle, exist."
Liquid crystals fall somewhere in between a liquid and a solid: they are made up of molecules that flow around freely as if they were a liquid but are all oriented in the same direction, as in a solid.
In a ‘quantum’ liquid crystal, electrons behave like the molecules in classical liquid crystals. That is, the electrons move around freely yet have a preferred direction of flow.
Postdoctoral scholar, John Harter, explains that 2D quantum liquid crystals behave in strange ways. "Electrons living in this flatland collectively decide to flow preferentially along the x-axis rather than the y-axis even though there's nothing to distinguish one direction from the other," he says.
In the recently discovered 3D version, the electrons not only make a distinction between the x, y, and z axes, but they also have different magnetic properties depending on whether they flow forward or backward on a given axis.
"Running an electrical current through these materials transforms them from nonmagnets into magnets, which is highly unusual," says Hsieh. "What's more, in every direction that you can flow current, the magnetic strength and magnetic orientation changes. Physicists say that the electrons 'break the symmetry' of the lattice."
Potential applications include spintronics and quantum computers.
"In the same way that 2D quantum liquid crystals have been proposed to be a precursor to high-temperature superconductors, 3D quantum liquid crystals could be the precursors to topological superconductors," says Hsieh.