December 2010 Volume 9, Issue 12

Editorial

More than just room temperature p951
doi:10.1038/nmat2918
Diluted magnetic semiconductors and oxides are interesting for fundamental science and applications even without room-temperature ferromagnetism.
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Commentary

A window on the future of spintronics pp952 - 954
Hideo Ohno
doi:10.1038/nmat2913
Despite low transition temperatures, ferromagnetism in diluted magnetic semiconductors has been essential in exploring new ideas and concepts in spintronics, some of which have been successfully transferred to metallic ferromagnets.
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Interviews

A model ferromagnetic semiconductor pp955 - 956
doi:10.1038/nmat2908
Nitin Samarth has extensive experience in studying the properties of (Ga,Mn)As. He told Nature Materials about the role that this compound has had in exploring the magnetic properties of semiconductors and, more generally, of spin-related phenomena.
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Is it really intrinsic ferromagnetism? pp956 - 957
doi:10.1038/nmat2905
Scott Chambers has worked on epitaxial oxide films for the past eighteen years. Nature Materials asked him about his view on high-temperature ferromagnetism in diluted magnetic oxides.
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Research Highlights

Our choice from the recent literature p958
doi:10.1038/nmat2917
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News and Views

Letters

Electric-field control of spin waves at room temperature in multiferroic BiFeO3  pp975 - 979
P. Rovillain, R. de Sousa, Y. Gallais, A. Sacuto, M. A. Méasson, D. Colson, A. Forget, M. Bibes, A. Barthélémy & M. Cazayous
doi:10.1038/nmat2899
Magnons are collective excitations of spins in a material, and just like individual electron spins, they could form the basis for novel computing concepts. Now, determination of the almost loss-less electrical switching of magnons at room temperature takes us a step closer to such ‘magnonic’ devices.
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Fast domain wall motion in magnetic comb structures pp980 - 983
E. R. Lewis, D. Petit, L. O’Brien, A. Fernandez-Pacheco, J. Sampaio, A-V. Jausovec, H. T. Zeng, D. E. Read and R. P. Cowburn
doi:10.1038/nmat2857
Domain walls in magnetic nanostructures could be used in information storage devices. The speed at which these domain walls can move when a magnetic field is applied has always been found to have a maximum. It is now shown that this can be increased by proper design of the magnetic structures, opening the way to faster and more reliable devices.
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See also: News and Views by Beach

Direct observation and mapping of spin waves emitted by spin-torque nano-oscillators pp984 - 988
Vladislav E. Demidov, Sergei Urazhdin and Sergej O. Demokritov
doi:10.1038/nmat2882
A spin-polarized current induces a spin torque on the magnetization of a ferromagnetic film, which according to theory leads to spin-wave emissions. These spin waves have now been observed with a mapping technique that shows a highly directional emission. The results are of key importance to understanding the physics of spin waves and their possible use in spintronic devices.
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An acoustic rectifier pp989 - 992
B. Liang, X. S. Guo, J. Tu, D. Zhang and J. C. Cheng
doi:10.1038/nmat2881
The detection of acoustic signals is of relevance for a range of practical applications, for example in medical diagnostics. However, in contrast to the rectification of electric current in diodes, acoustic rectification has not yet been achieved. The first experimental demonstration of an acoustic rectifier therefore promises significant impact for practical applications.
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See also: News and Views by Li

Direct observation of the temporal and spatial dynamics during crumpling pp993 - 997
Hillel Aharoni and Eran Sharon
doi:10.1038/nmat2893
Although crumpled sheets have large resistance to compression, little is known about the dynamical evolution of their three-dimensional spatial configurations. The formation of a network of ridges and vertices into which the energy is localized is now observed during dynamic crumpling under isotropic confinement.
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Selective catalysts for the hydrogen oxidation and oxygen reduction reactions by patterning of platinum with calix[4]arene molecules pp998 - 1003
Bostjan Genorio, Dusan Strmcnik, Ram Subbaraman, Dusan Tripkovic, Goran Karapetrov, Vojislav R. Stamenkovic, Stane Pejovnik and Nenad M. Marković
doi:10.1038/nmat2883
Cathode degradation and methods for improving the selectivity of anode catalysts remain crucial challenges for the design of polymer electrolyte membrane fuel cells. A chemically modified Pt electrode with a self-assembled monolayer of calix[4]arene molecules is now shown to selectively block the undesired oxygen reduction reaction.
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The role of collagen in bone apatite formation in the presence of hydroxyapatite nucleation inhibitors pp1004 - 1009
Fabio Nudelman, Koen Pieterse, Anne George, Paul H. H. Bomans, Heiner Friedrich, Laura J. Brylka, Peter A. J. Hilbers, Gijsbertus de With and Nico A. J. M. Sommerdijk
doi:10.1038/nmat2875
The role of collagen in bone apatite mineralization has so far remained unclear. Now, on combining cryogenic electron microscopy and in vitro systems, it is shown that collagen works alongside inhibitors of hydroxyapatite nucleation to control infiltration of amorphous calcium phosphate into collagen fibrils and convert the amorphous phase into apatite crystals.
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See also: News and Views by Cölfen

The role of prenucleation clusters in surface-induced calcium phosphate crystallization pp1010 - 1014
Archan Dey, Paul H. H. Bomans, Frank A. Müller, Julia Will, Peter M. Frederik, Gijsbertus de With and Nico A. J. M. Sommerdijk
doi:10.1038/nmat2900
The surface-directed mineralization of calcium phosphate from simulated body fluid is studied by cryogenic transmission electron microscopy. Prenucleation clusters aggregate close to the surface, then amorphous calcium phosphate forms in this region, leading to the nucleation of oriented apatite crystals at the surface.
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See also: News and Views by Cölfen

Articles

Flexible organic transistors and circuits with extreme bending stability pp1015 - 1022
Tsuyoshi Sekitani, Ute Zschieschang, Hagen Klauk and Takao Someya
doi:10.1038/nmat2896
Strain-induced damage typically limits the bending radius of electronic circuits to a few millimetres. The development of very thin organic transistors and electronic circuit designs that show a bending radius down to 100 μm will enable novel applications with unconventional form factors.
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An engineered anisotropic nanofilm with unidirectional wetting properties pp1023 - 1028
Niranjan A. Malvadkar, Matthew J. Hancock, Koray Sekeroglu, Walter J. Dressick and Melik C. Demirel
doi:10.1038/nmat2864
Hydrophobic surfaces composed of an asymmetric array of polymer nanorods show unidirectional wetting behaviour relative to the orientation of the tilted nanorods. The surfaces, which are smooth on the microscale, can transport water droplets of microlitre capacity by a ratcheting mechanism resulting from the pillared substrate.
Abstract | Full Text | PDF