#spin liquids

Material previously thought to be quantum is actually a new, non-quantum state of matter

Magnetic materials in a quantum spin liquid phase are of great interest in the pursuit of exotic state of matter and quantum computation. But in the quantum realm, things are not always what they seem. A study, published in Science Advances and co-led by Rice University's Pengcheng Dai, found that the material cerium magnesium hexalluminate (CeMgAl11O19) was not actually in a quantum spin liquid phase despite evidence suggesting it was. "The material had been classified as a quantum spin liquid due to two properties: observation of a continuum of states and lack of magnetic ordering," said Bin Gao, co-first author and a research scientist at Rice. "But closer observation of the material showed that the underlying cause of these observations wasn't a quantum spin liquid phase."

Quantum witness technique reveals spinons in quantum spin liquid candidate

Physicists at University College Cork have developed a new approach in the search for a quantum spin liquid, a long-sought state of quantum matter resembling a magnetic liquid whose quantum properties mean it never freezes. The work is a key step in the search for quantum silicon, a mineral that could be used to create quantum computers, just as silicon is used in traditional computers. The resulting paper appears in Nature Physics. Lead author Prof. Seamus Davis said, "By introducing the quantum witness technique we provide a completely new perspective on the physics of quantum spin liquids and access their internal quantum excitations or 'spinons' directly for the first time at UCC."

Evidence of a quantum spin liquid ground state in a kagome material

Quantum spin liquids are exotic states of matter in which spins (i.e., the intrinsic angular momentum of electrons) do not settle into an ordered pattern and continue to fluctuate, even at extremely low temperatures. This state is characterized by high entanglement, a quantum effect that causes particles to become linked so that the state of one affects the others' states, even over long distances. Researchers at SLAC National Accelerator Laboratory and Stanford University recently gathered evidence of intrinsic quantum spin liquid behavior in a kagome material, a magnetic material in which atoms are arranged in a particular pattern known as a kagome lattice. Their findings, published in Nature Physics, could help to further delineate the fundamental principles underpinning quantum spin liquid states. "I've been interested in understanding quantum spin liquids for the past 20+ years," Young S. Lee, senior author of the paper, told Phys.org. "These are fascinating new states of quantum matter. In principle, their ground states may possess long-range quantum entanglement, which is extremely rare in real materials.

New route to quantum spin liquid materials discovered

A new route to materials with complex disordered magnetic properties at the quantum level has been produced by scientists for the first time. The material, based on a framework of ruthenium, fulfills the requirements of the Kitaev quantum spin liquid state—an elusive phenomenon that scientists have been trying to understand for decades. Published in Nature Communications, the study by scientists at the University of Birmingham offers an important step towards achieving and controlling quantum materials with sought-after new properties that do not follow classical laws of physics. Crucially, the materials provide a route to magnetic properties which behave differently from conventional "ferromagnets," ordered around two poles. Ferromagnets—which include the familiar bar magnets found on fridges or noticeboards—contain electrons which interact with each other, each functioning as a tiny magnet to attract and repel, so that they all point in the same direction, giving the magnet its force.

A quantum spin liquid

Honeycomb lattice meets elusive standards of the Kitaev model

Researchers from Boston College and Harvard have created an elusive honeycomb-structured material capable of frustrating the magnetic properties within it in order to produce a chemical entity known as "spin liquid," long theorized as a gateway to the free-flowing properties of quantum computing, according to a new report in the Journal of the American Chemical Society.

The first-of-its-kind copper iridate metal oxide -- Cu2IrO3 -- is one where the natural magnetic order is disrupted, a state known as geometric frustration, said Boston College Assistant Professor of Physics Fazel Tafti, a lead author of the study, titled Cu2IrO3: a new magnetically frustrated honeycomb iridate.

The copper iridate is an insulator -- its electrons are immobilized in the solid -- but they can still transport a magnetic moment known as "spin." The transport of free spins in the material allows for a flow of quantum information.

The Kitaev model, proposed in 2006 by Cal Tech Professor of Physics Alexei Kitaev, states that a hexagonal honeycomb structure offered a promising route to geometric frustration and therefore, to quantum spin liquid.