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SIMaP laboratory publishes scientific results in various peer-reviewed international journals. List of those papers and more can be found on the open archive HAL.

Physical Review Letters: Band Filling Control of the Dzyaloshinskii-Moriya Interaction in Weakly Ferromagnetic Insulators

PhysRevLet_carbonatesAn international team of scientists have uncovered a surprisingly simple trend in the behaviour of 'twisted' magnets, which is precisely mirrored by first-principles calculations and explained by a simple microscopic model.
While the twisting of individual atomic-scale magnets is set to play a prominent role in future 'spintronics' technologies, the phenomenon was first discussed in detail in the context of 'weak ferromagnets' over half a century ago. It is precisely these materials that now offer a unique opportunity to investigate the effects of changing the magnetic atom type, since this causes almost no change in their structure.
Unfortunately, the direction of the magnetic twists cannot be observed by conventional techniques, since the two twist directions look the same. The researchers overcame this limitation by borrowing ideas from holography and applying them to x-ray 'diffraction', carried out at two of Europe's most powerful x-ray sources: Diamond Light Source in the UK and the European Synchrotron Radiation Source in France. The new technique gave a clear fingerprint of the twist direction, as the magnetic atoms gradually progressed along a row of the periodic table of elements. The results showed a sudden reversal of the twist, between manganese and iron, to the heavier cobalt and nickel atoms. Moreover, the jump is exactly as predicted by theory.
The team are hopeful that their results will bring new insights into an important class of material, and that their technique can be extended to other problems in solid state physics. The success of the computer simulations brings us a small step closer to goal of predicting the properties of technologically-important materials.

Band Filling Control of the Dzyaloshinskii-Moriya Interaction in Weakly Ferromagnetic Insulators
, G. Beutier, S. P. Collins, O. V. Dimitrova, V. E. Dmitrienko, M. I. Katsnelson, Y. O. Kvashnin, A. I. Lichtenstein, V. V. Mazurenko, A. G. A. Nisbet, E. N. Ovchinnikova, and D. Pincini, Phys. Rev. Lett. 119, 167201,

Coatings journal front cover: Design of Experiments method: a fountain of Youth for CVD process.

CVD SIMaP (credit F. Mercier)We propose here to revisit a classical CVD process with a design of experiment approach to reveal that main parameters influencing the desired properties of an epitaxial layer, here AlN on sapphire, are not necessarily the one you expect. Simple DOE method can bring new insight into a well-established research and can make you go out of your intuition without any increase in experimental cost !
This work is published in Coatings and is enlighten in the front cover of 2017 September issue

Epitaxial Growth of AlN on (0001) Sapphire: Assessment of HVPE Process by a Design of Experiments Approach,
Raphaël Boichot, Danying Chen, Frédéric Mercier, Francis Baillet, Gaël Giusti, Thomas Coughlan, Mikhail Chubarov and Michel Pons, Coatings 2017, 7(9), 136; doi: Coatings 2017, 7(9), 136; doi:10.3390/coatings7090136

ESRF Spotlight: Fast in-situ nanoimaging of particle sintering

ESRF Spotlight Fast in situ imaging
Neck curvature, a parameter critical to the understanding of sintering, was determined precisely for the first time for the sintering of a glass powder. This was achieved by studying the microstructure evolution during sintering by high-temperature in-situ nanotomography using an unprecedented combination of fast scan time and high resolution. Those results are gathered in a paper in Materials Today journal and are also the subject of a ESRF' SPOTLIGHT ON SCIENCE.

Fast in situ 3D nanoimaging: a new tool for dynamic characterization in materials science, J. Villanova, R. Daudin, P. Lhuissier, D. Jauffrès, S. Lou, C.L. Martin, S. Labouré, R. Tucoulou, G. Martínez-Criado, L. Salvo, Materials Today (2017); doi: 10.1016/j.mattod.2017.06.0

Scientific Reports: From powders to bulk metallic glass composites.

Metallic glass composites
One way to adjust the properties of a material is by changing its microstructure. This concept is not easily applicable on bulk metallic glasses (BMGs), because they do not consist of grains or different phases and so their microstructure is very homogeneous. One obvious way to integrate inhomogeneities is to produce bulk metallic glass composites (BMGCs). Here we show how to generate BMGCs via high-pressure torsion (HPT) starting from powders (amorphous Zr-MG and crystalline Cu). This approach has been developed in partnership with the Erich Schmid Institute of Materials Science in Leoben, Austria, and demonstrated that by changing the applied shear strains, the refinement of the microstructure is adjustable. The refinement of microstructure increases the hardness and a hardness higher than the initial BMG can be obtained.

From powders to bulk metallic glass composites
Lisa Krämer, Yannick Champion, Rienhard Pipan, Scientific Reports (2017)

Date of update January 11, 2019

Univ. Grenoble Alpes