Effect of short range order on electronic and magnetic properties of disordered Co based alloys

We here study electronic structure and magnetic properties of disordered CoPd and CoPt alloys using Augmented Space Recursion technique coupled with the tight-binding linearized muffin tin orbital (TB-LMTO) method. Effect of short range ordering present in disordered phase of alloys on electronic and magnetic properties has been discussed. We present results for magnetic moments, Curie temperatures and electronic band energies with varying degrees of short range order for different concentrations of Co and try to understand and compare the magnetic properties and ordering phenomena in these systems.Comment: 15 pages,17 postscript figures,uses own style file

Defect‐Driven Magnetization Configuration of Isolated Linear Assemblies of Iron Oxide Nanoparticles

International audienceThe magnetization state of one-dimensional magnetic nanoparticle chains plays a key role for a wide range of applications ranging from diagnosis and therapy in medicine to actuators, sensors and quantum recording media. The interplay between the exact particle orientation and the magnetic anisotropy is in turn crucial for controlling the overall magnetization state with high precision. Here, we report on a three-dimensional description of the magnetic structure of one-NP-wide chains. In this aim, we combined two complementary experimental techniques, magnetic force microscopy (MFM) and electronic holography (EH) which are sensitive to out-of-plane and in-plane magnetization components, respectively. We extended our approach to micromagnetic simulations which provided results in good agreement with MFM and EH. The findings are at variance with the known results on unidirectional nanoparticle assemblies, and show that magnetization is rarely strictly collinear to the chain axis. The magnetic structure of one-NP-wide chains can be interpreted as head-to-head magnetic domain structures with off-axis magnetization components, which is very sensitive to morphological defects in the chain structure such as minute size variation of NPs, tiny misalignment of NPs and/or crystal orientation with respect to easy magnetization axis

Magnetic properties of X-Pt (X=Fe,Co,Ni) alloy systems

We have studied the electronic and magnetic properties of Fe-Pt, Co-Pt and Ni-Pt alloy systems in ordered and disordered phases. The influence of various exchange-correlation functionals on values of equilibrium lattice parameters and magnetic moments in ordered Fe-Pt, Co-Pt and Ni-Pt alloys have been studied using linearized muffin-tin orbital method. The electronic structure calculations for the disordered alloys have been carried out using augmented space recursion technique in the framework of tight binding linearized muffin-tin orbital method. The effect of short range order has also been studied in the disordered phase of these systems. The results show good agreements with available experimental values.Comment: 21 pages, 4 eps figures, accepted for publication in Journal of Physics Condensed Matte

Diffuse scattering

Diffuse neutron scattering covers a wide range of phenomena related to short range nuclear and magnetic orderings. Although it is “a priori” simple to measure, the underlying physics is often quite complex. Extracting useful and reliable information requires careful corrections and calibrations, and appropriate models of analysis, specifics for each physical case. This paper yields a partial and subjective glance on this specific subject, showing studies about chemical orderings in binary alloys and magnetic correlations in frustrated “spin ices” as examples

Femmes et Physique, la commission reprend du service

La commission « Femmes et Physique » de la Société Française de Physique a pour objectif d’attirer, d’encourager et de promouvoir les femmes dans les métiers de la physique(1

Séminaire “Women in Science” à Bangalore

Du 3 au 5 févier 2015 a eu lieu à Bangalore (Inde) un séminaire franco-indien « Femmes en Sciences », soutenu par le CEFIPRA, et qui a réuni 250 participantes indiennes, 9 participantes françaises et une dizaine d’hommes. Le séminaire a mis en relief la science faite par des femmes dans le cadre de collaborations franco-indiennes en mathématiques, physique et biologie, et a été l’occasion d’une table ronde sur le problème des femmes en sciences : comment le CEFIPRA peut-il aider à améliorer leur place, en Inde en particulier