Instability of the rhodium magnetic moment as origin of the metamagnetic phase transition in alpha-FeRh

Based on ab initio total energy calculations we show that two magnetic states of rhodium atoms together with competing ferromagnetic and antiferromagnetic exchange interactions are responsible for a temperature induced metamagnetic phase transition, which experimentally is observed for stoichiometric alpha-FeRh. A first-principle spin-based model allows to reproduce this first-order metamagnetic transition by means of Monte Carlo simulations. Further inclusion of spacial variation of exchange parameters leads to a realistic description of the experimental magneto-volume effects in alpha-FeRh.Comment: 10 pages, 13 figures, accepted for publication in Phys. Rev.

Haematopoietic SCT in severe autoimmune diseases: updated guidelines of the European Group for Blood and Marrow Transplantation

In 1997, the first consensus guidelines for haematopoietic SCT (HSCT) in autoimmune diseases (ADs) were published, while an international coordinated clinical programme was launched. These guidelines provided broad principles for the field over the following decade and were accompanied by comprehensive data collection in the European Group for Blood and Marrow Transplantation (EBMT) AD Registry. Subsequently, retrospective analyses and prospective phase I/II studies generated evidence to support the feasibility, safety and efficacy of HSCT in several types of severe, treatment-resistant ADs, which became the basis for larger-scale phase II and III studies. In parallel, there has also been an era of immense progress in biological therapy in ADs. The aim of this document is to provide revised and updated guidelines for both the current application and future development of HSCT in ADs in relation to the benefits, risks and health economic considerations of other modern treatments. Patient safety considerations are central to guidance on patient selection and HSCT procedural aspects within appropriately experienced and Joint Accreditation Committee of International Society for Cellular Therapy and EBMT accredited centres. A need for prospective interventional and non-interventional studies, where feasible, along with systematic data reporting, in accordance with EBMT policies and procedures, is emphasized

Magnetic excitation in CuMn spin glass alloy

The spin dynamics of a spin glass alloy Cu/sub 78/ /sub 7/Mn/sub 21/ /sub 3/ have been studied by neutron inelastic scattering. Measurements have been made at 20/sup 0/K, 150/sup 0/K, and 290/sup 0/K by the constant E mode of operation. Magnetic excitations with rather large energy transfer have been observed around the (1-1/2 O) and the (1-1/2+-delta O) magnetic diffuse peak positions above and below the spin freezing temperature (T/sub f/ approx. 90/sup 0/K). The results indicate the existence of strong space and time correlations of the spins over the temperature range of the measurements. The experimental data are well explained by a model of dynamically fluctuating spin clusters with a broad distribution of relaxation times

PHONON DISPERSION RELATION OF MASS DEFECT CONCENTRATED ALLOY Ni-Pt AND ITS INTERPRETATION BY CPA

Relation de Dispersion pour les Phonons dans les Alliages concentrés Ni-Pt avec défaut de masse. Les vibrations atomiques dans des cristaux simples de l'alliage Ni-Pt ont été étudiées au moyen de la diffusion inélastique de neutrons. Des mesures ont été effectuées pour les branches [00ζ] T. Les résultats sont comparés avec des calculs basés sur la CPA.By means of inelastic scattering of neutrons, the phonon dispersion relations of 00ζ T branch have been measured for Ni-Pt alloys with various concentrations. For Ni95Pt5 and Ni70Pt30, double peaks were found in the neutron scattering spectra obtained by constant q method at about q = 0.5. The dispersion relation has an energy gap corresponding to the appearance of the double peaks. The gap with is about 3 meV and 6 meV for Ni95Pt5 and Ni70Ni30, respectively. Taylor has calculated the spectral Green function of phonons in mass defect concentrated alloy AuCu under CPA. From the positions and widths of the peaks of the Green function, one can construct the dispersion curves of phonon mode as well as width. The theoretical dispersion relation, thus obtained has an energy gap corresponding to the localized vibrations. The similarity of the theoretical and experimental dispersion relations indicates that the nature of phonons in highly concentrated mass defect alloys can be well interpreted by the theory under CPA. The reason of the appearance of the double phonons corresponding to a single wave number can be understood by considering that the vibration frequency of an atom changes in time or in space from higher one which is a localized mode around light atoms to lower one which is a localized mode around heavy atoms

ATOMIC MAGNETIC MOMENT IN TERNARY ALLOY Fe-Co-Ni

On a observé les moments magnétiques atomiques de Co et Fe dans l'alliage ternaire Fe-Co-Ni cubique à faces centrées. Les résultats sont expliqués au moins qualitativement par une théorie CPA.The atomic magnetic moments of Co and Fe were observed in f.c.c. ternary Fe-Co-Ni alloys. The results are explained by CPA theory at least qualitatively