News

New quantum spin liquid predicted by Nobel Laureate prepared for the first time

This achievement is an important step towards building so-called topological quantum computers.
The magnetically ordered square lattice of copper ions. Tailoring the structure caused the formation of quantum spin liquid. Modifying the structure in a different way results in high-temperature superconductivity. Photo: Otto Mustonen

In 1987 Paul W. Anderson, a Nobel Prize winner in Physics, proposed that high-temperature superconductivity, or loss of electrical resistance, is related to an exotic quantum state now known as quantum spin liquid. Magnetic materials are made up of very tiny magnets, which can be as small as individual electrons. The strength and direction of these are described by the magnetic moment. In quantum spin liquids, magnetic moments behave like a liquid and do not freeze or order even at absolute zero. These quantum states are being studied as promising materials for new, so-called topological quantum computers, in which operations are based on particle-like excited states found in quantum spin liquids. In addition to large computational power, a topological quantum computer is characterised by high fault tolerance, which makes it possible to increase the size of the computer. However, only a few quantum spin liquids suitable for topological quantum computers have been identified so far.

A method of tailoring the magnetism of materials developed at Aalto enabled the preparation of a new quantum spin liquid

Now, for the first time ever, researchers from Aalto University, Brazilian Center for Research in Physics (CBPF), Technical University of Braunschweig and Nagoya University have produced the superconductor-like quantum spin liquid predicted by Anderson. This is an important step towards understanding superconductors and quantum materials. The preparation of a quantum spin liquid was made possible by a new way of tailoring the properties of magnetic materials that was developed by chemists at Aalto University. The results of the research have been published in Nature Communications.

High-temperature superconductors are copper oxides in which the copper ions form a square lattice so that the adjacent magnetic moments face in opposite directions. When this structure is disturbed by changing the oxidation state of copper, the material becomes superconducting. In the new research now published, the magnetic interactions of this square structure were modified with ions with a d10 and d0 electronic structure, which turned the material into a quantum spin liquid. 

“In the future, this new d10/d0 method can be utilised in many other magnetic materials, including various quantum materials”, envisions Doctoral Candidate Otto Mustonen from Aalto University.

Seamless cooperation

Empirical detection of quantum spin liquids is difficult and requires extensive research infrastructure.

“We used muon spin spectroscopy in the this study. This method is based on the interaction of very short-lived, electron-like elementary particles, known as muons, with the material being studied. The method can detect very weak magnetic fields in quantum materials”, says Professor F. Jochen Litterst from the Technical University of Braunschweig. The measurements were performed at the Paul Scherrer Institute in Switzerland.

 

The muon spin spectrometer used in the study at the Paul Scherrer Institute. The sample being studied is placed in the cryostat located in the middle, and a muon beam is aimed at it from the back left direction. Photo: Otto Mustonen

“In addition to top-class equipment, the research requires seamless cooperation between chemists and physicists”, emphasises Professor Maarit Karppinen. “We’re going to need the same international multidisciplinary approach in the future so that this research on quantum spin liquids can lead us to the experimental realization of the topological quantum computer.”

Further information:

Otto Mustonen
[email protected]

Distinguished Professor Maarit Karppinen
[email protected]
tel. +358 50 384 1726

Article:

O. Mustonen, S. Vasala, E. Sadrollahi, K. P. Schmidt, C. Baines, H. C. Walker, I. Terasaki, F. J. Litterst, E. Baggio-Saitovitch & M. Karppinen, Spin-liquid-like state in a spin-1/2 square-lattice antiferromagnet perovskite induced by d10–d0 cation mixing, Nature Communications volume 9, Article number: 1085 (2018)

DOI:10.1038/s41467-018-03435-1
http://www.nature.com/articles/s41467-018-03435-1

 

  • Published:
  • Updated:
Share
URL copied!

Related news

Learning Centre graphics
Research & Art Published:

Dawsonera database has been shut down

Dawsonera database has been shut down due to its provider’s going into administration.
Woman wearing an orange-colored dress and standing on the grass in between birch trees
Research & Art Published:

From her own little world to the other side of the globe

Her studies and her parents used to be her whole world, but now Dr. Avleen Malhi lives on the other side of the world, designs an Airbnb for car drivers, and encourages women to pursue their goals
Magnetic materials
Research & Art Published:

A road to frustration

Aalto University theorist part of a team that opens up a new route to design exotic frustrated
quantum magnets.
Pohjoisen ikirouta-alueen vehreää kasvillisuutta. Kuva: Ive van Krunkelsven
Press releases, Research & Art Published:

Greenhouse gas emissions from permafrost area larger than earlier estimated

Plant roots in soil stimulate microbial decomposition, a mechanism called the priming effect. A recent study published in Nature Geoscience shows that the priming effect alone can cause emission of 40 billion tonnes carbon from permafrost by 2100.