Their work, one of the very few studies of this particular spin state, which has been postulated as a possible underlying mechanism for high-temperature superconductivity, may eventually serve as a test of current and future theoretical models of exotic spin states.
At the NIST Center for Neutron Research (NCNR) and the Hahn-Meitner Institute in Berlin, Germany, the scientists used intense beams of neutrons to probe a series of antiferromagnets, materials in which each spin—an intrinsic property of an atom that produces a tiny magnetic field called a magnetic “moment”—cancels another, giving the material a net magnetic field of zero. The results, described in the Aug. 26 online edition of Nature Materials,* revealed evidence of a rare and pporly understood “quantum paramagnetic” spin state, in which neighboring spins pair up to form “entangled spin singlets” that have an ordered pattern and that allow the material to weakly respond to an outside magnetic field—i.e., become paramagnetic.
The antiferromagnets used in this work are composed mainly of zinc and copper, and are distinguished by their proportions of each, with the number of copper ions determined by the number of zinc ions. At the atomic level, the material is formed of many repeating layers. The atoms of each layer are arranged into a structure known as a “kagome lattice,” a pattern of triangles laid point-to-point whose basic unit resembles a six-point star.
Physicists have been studying antiferromagnets with kagome structures over the last 20 years because they suspected these materials harbored interesting spin structures. But good model systems, like the zinc/copper compounds used by this group, had not been identified.
At the NCNR, the researchers determined how varying concentrations of zinc and copper and varying temperatures affected fluctuations in the way the spins are arranged in these materials. Using a neutron spectrometer at the Hahn-Meitner Institute, they also investigated the effect of external magnetic fields of varying strengths. The group uncovered several magnetic phases in addition to the quantum paramagnetic state and were able to construct a complete phase diagram as a function of the zinc concentration and temperature. They are planning further experimental and theoretical studies to learn more about the kagome system.
Laura Mgrdichian | EurekAlert!
Decoding cement's shape promises greener concrete
08.12.2016 | Rice University
Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D
08.12.2016 | DOE/Brookhaven National Laboratory
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine