Press releases
Please quote Nature Materials as the source of these items.
February 2008
Towards a 'cloak' for magnetic fields
An artificial superconductor structure, also known as a metamaterial, that could be used to make devices capable of screening magnetic fields is reported online this week in Nature Materials. The devices could be used for applications such as protecting electronic circuits or sensitive diagnostic tools.
Metamaterials have already attracted considerable interest for their ability to guide light in ways impossible to achieve by conventional optical elements such as lenses. They have been used to demonstrate 'cloaking', where light of a particular wavelength is guided around an object to make it appear invisible.
Ben Wood and colleagues present a metamaterial structure, based on an array of superconducting elements that could be used to 'cloak' static magnetic fields, instead of light waves, by guiding them away from the inner region of the structure.
A d.c. magnetic metamaterial pp295 - 297
F. Magnus, B. Wood, J. Moore, K. Morrison, G. Perkins, J. Fyson, M. C. K. Wiltshire, D. Caplin, L. F. Cohen, J. B. Pendry
doi 10.1038/nmat2126
Multiferroics heat up
Scientists have discovered a new class of materials that have a multiferroic state -- that is stable at higher temperatures than previously known. The study, reported online this week in Nature Materials, could prove promising for the sensing of magnetic fields or future data storage applications.
For such applications, those multiferroic materials that have a strong coupling between the magnetic and electric properties are of particular interest. However, so far these have mostly only worked at temperatures below 40 Kelvin. The discovery by Tsuyoshi Kimura and colleagues of a new class of these materials, based on cupric oxide (CuO), where the multiferroic state is stable up to 230 Kelvin, therefore represents a significant advance. In a way, this stability of CuO is reminiscent of high-temperature superconductors, for which CuO is an important building block. As Maxim Mostovoy points out in an accompanying News & Views article, this discovery opens a new hunting ground for high-temperature multiferroic materials based on copper oxides.
Cupric oxide as an induced-multiferroic with high-TC pp291 - 294
T. Kimura, Y. Sekio, H. Nakamura, T. Siegrist, A. P. Ramirez
doi 10.1038/nmat2125
Physics at the beach
Scientists have proposed an explanation for why structures such as sandcastles can be built so easily without a recipe for the exact combination of sand and water needed. The study, online this week in Nature Materials, should prove useful for clarifying how grain-liquid-air interfaces interact.
The insensitivity of the mechanical properties of wet granular matter to their liquid content is not well understood. Stephan Herminghaus and colleagues used X-ray microtomography to demonstrate that this behaviour results from the organization of the liquid in the grain pile into a variety of bridges and clusters. For spherical as well as non-spherical grains, such as sand, a simple geometric rule relating the macroscopic properties, for example stability, to the internal liquid morphologies is proposed.
Such imaging techniques could clarify how grain-liquid-air interfaces interact and possibly prevent grain segregation, particle agglomeration and even landslides.
