The properties of a material are greatly affected by the electrical and magnetic structure of its constituent ions and electrons. In a ferromagnet, for example, neighboring electron spins point in the same direction, producing a strong external magnetic field. In an antiferromagnet, however, neighboring spins point in opposite directions, negating its magnetism. This behavior can be exploited in devices ranging from switches to memory and computers.
Figure 1: A one-dimensional chain of spins (red arrows), showing a chiral ordering (or spiral), which rotate (blue arrows) in response to incoming light radiation. Copyright : 2011 The American Physical Society
Multiferroic materials exhibit an even richer physics—and an expanded set of applications—because their magnetic and electrical orderings are linked. However, the magnetic and electrical structuring of multiferroics is not yet completely understood. Now, Shunsuke Furukawa, Masahiro Sato and Shigeki Onoda of the RIKEN Advanced Science Institute, Wako, have successfully calculated how magnetic ordering arises in one-dimensional multiferroic materials—the simplest example of these materials.
This simplicity means that one-dimensional multiferroic materials are useful models for understanding multidimensional, or ‘bulk’, multiferroic materials. Their one-dimensional chain of spins can not only assume a variety of ferromagnetic and anti-ferromagnetic alignments, but they can also arrange into more complicated patterns, including spirals defined over long portions of the chain—referred to as ‘long-range chiral order’ (Fig. 1). Understanding these exotic patterns may lead to new foundational science, as well as new applications. In addition, a one-dimensional chain can also exhibit the electrical control of magnetic structure and the response to light that is characteristic of more complex multiferroics.
Onoda and colleagues focused on describing the magnetic structure in a one-dimensional chain in terms of how strongly neighboring spins were coupled to each other. They began by using a computational technique that uniquely allows for the accurate treatment of an infinitely large collection of spins to construct a phase diagram describing how spin ordering changed as the type of spin-to-spin coupling in the material changed. Most notably, the diagram indicated that ferromagnetic coupling between nearest neighbors was much more likely to cause a long-range chiral order than anti-ferromagnetic coupling.
This observation successfully explained the experimentally observed spin ordering of several one-dimensional multiferroic cuprates. In particular, the research team was able to correctly predict that the bulk multiferroic material LiCu2O2, whose unique physics has drawn the attention of physicists for over a decade, exhibits chiral order and has a unique response to light. "These results confirm that one-dimensional multiferroics are an ideal laboratory for studying spin dynamics", says Onoda, and he feels that the calculations will promote studies on new one-dimensional multiferroics and other novel states of matter.
The corresponding author for this highlight is based at the Condensed Matter Theory Laboratory, RIKEN Advance Science Institute
 Furukawa, S., Sato, M. & Onoda, S. Chiral order and electromagnetic dynamics in one-dimensional multiferroic cuprates. Physical Review Letters 105, 257205 (2010).
gro-pr | Research asia research news
SF State astronomer searches for signs of life on Wolf 1061 exoplanet
20.01.2017 | San Francisco State University
Molecule flash mob
19.01.2017 | Technische Universität Wien
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
20.01.2017 | Awards Funding
20.01.2017 | Materials Sciences
20.01.2017 | Life Sciences