RSS icon
Twitter icon
Facebook icon
Vimeo icon
YouTube icon

Kaleidoscope of Exotic Quantum Phases in a Frustrated XY Model

Figure: Above: Antiferromagnetic arrangement of spins. Below: Arrangement of spins in a spin liquid, where there is no magnetic order. Author Galitski describes the spins as free ranging particle-like entities dubbed “spinons.” These spinons bob about, just as water molecules bob about in liquid water. (Image credit: E. Edwards)

PFC-supported research at JQI has uncovered evidence for a long-sought-after quantum state of matter, a spin liquid. You can’t pour a spin liquid into a glass.  It’s not a material at all, at least not a material you can touch. It is more like a kind of magnetic disorder within an ordered array of atoms.

Spin liquids arise due to “frustration,” a baffling condition wherein neighboring atom spins try to anti-align in up-down-up-down fashion, but are prevented from doing so by the intrinsic geometry of the lattice (here, a honeycomb). Understanding frustration and the different ways a collection of magnetically interacting spins can arrange themselves might help in designing new types of electronic circuitry.

One compromise that a frustrated spin system makes is to simultaneously exist in many spin orientations . The researchers uncovered a spin liquid when exploring frustration in materials with a hexagonal (six-sided) unit cell lattice. They calculated what happened when a batch of atoms interacted among themselves in an array of hexagons consisting of 30 sites, where the spins are free to swing about in a two-dimensional plane (this kind of approach is called an XY model).

They found a “kaleidoscope” of phases that represent the different lowest-energy states that are allowed given a range of magnetic interactions. One of these phases turns out to be a true quantum spin liquid having no order at all.  Here, the entire sample co-exists in millions of quantum states simultaneously.

Researchers
Christopher N. Varney, Kai Sun, Victor Galitski, and Marcos Rigol
Reference Publication
Available Downloads

Subscribe to A Quantum Bit 

Quantum physics began with revolutionary discoveries in the early twentieth century and continues to be central in today’s physics research. Learn about quantum physics, bit by bit. From definitions to the latest research, this is your portal. Subscribe to receive regular emails from the quantum world. Previous Issues...

Sign Up Now

Sign up to receive A Quantum Bit in your email!

 Have an idea for A Quantum Bit? Submit your suggestions to jqi-comm@umd.edu