Magnetic, temperature and structural studies have yielded new insights on the material sodium iridium oxide
RIKEN scientists have discovered a new state of matter with unusual magnetic properties—its constituent electrons are in a continuous state of flux, even at incredibly cold temperatures.
As electrons spin, they generate a magnetic field which can point ‘up’ or ‘down’. Within solid materials, an electron will generally try to adopt the opposite spin orientation to its neighbor, just as two bar magnets will flip around so that north and south poles line up next to each other.
In more common lattice structures, where atoms stack up like oranges on a greengrocers stall, it’s easy for electrons to achieve this ordered arrangement. But in certain materials, the arrangement of atoms can make it impossible for the electrons to line up with all of their neighbors, and they are said to be ‘frustrated’.
One example of a frustrated material contains a network of atoms arranged into corner-sharing triangles. This is called a kagome structure after a type of Japanese basket that has the same pattern (Fig. 1).
The electrons’ response to this frustration is to constantly flip their magnetic fields to reduce the repulsion between them. In this ‘quantum spin-liquid state’, the quantum effect is expected to stop flipping electrons from freezing out into a static arrangement even at absolute zero (-273.15 ˚C—the coldest temperature possible). Several materials have been claimed to contain possible quantum spin-liquid states, but none have been confirmed.
Hidenori Takagi and Yoshihiko Okamoto of RIKEN’s Discovery Research Institute, Wako, and colleagues, have now found that sodium iridium oxide (Na4Ir3O8) exhibits quantum spin-liquid behavior, even when cooled to -271 ˚C. This was confirmed by magnetic, temperature and structural studies, involving both neutron and x-ray diffraction.
The material contains a network of iridium atoms that form a three-dimensional pattern of corner-shared triangles—dubbed a hyperkagome lattice (Fig. 2), which can be viewed as a slightly twisted—but different structure—to the kagome structure, explains Takagi. Theoretical calculations are consistent with this type of structure showing spin-liquid behavior.
“We believe it is the strongest candidate [for a quantum spin liquid],” says Takagi.
The scientists say that the material is “a fascinating playground for quantum magnetism”, and now hope to study the spin-liquid state further. This should to help build up a detailed description of the phenomenon using quantum theory, describing on a subatomic level exactly how the spinning electrons interact with each other.
1. Okamoto, Y., Nohara, M., Aruga-Katori, H. & Takagi, H. Spin-liquid state in the S = 1/2 hyperkagome antiferromagnet Na4Ir3O8. Physical Review Letters 99, 137207 (2007).
New gel-like coating beefs up the performance of lithium-sulfur batteries
22.03.2017 | Yale University
Pulverizing electronic waste is green, clean -- and cold
22.03.2017 | Rice University
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
23.03.2017 | Life Sciences
23.03.2017 | Power and Electrical Engineering
23.03.2017 | Earth Sciences