نتایج جستجو برای: pt alloys
تعداد نتایج: 89905 فیلتر نتایج به سال:
The complex correlation of structure and magnetism in highly coercive monoatomic FePt surface alloys is studied using scanning tunneling microscopy, x-ray magnetic circular dichroism, and ab initio theory. Depending on the specific lateral atomic coordination of Fe either hard magnetic properties comparable to that of bulk FePt or complex noncollinear magnetism due to Dzyaloshinski-Moriya inter...
We carry out ab initio calculations which demonstrate the importance of the non-spin-conserving part of the spin-orbit interaction for the intrinsic anomalous Hall conductivity of ordered FePt alloys. The impact of this interaction is strongly reduced if Pt is replaced by the lighter isoelectronic element Pd. An analysis of the interband transitions responsible for the anomalous velocity reveal...
2014 While the existence of a phase transition at finite Tc is well admitted for Ising spin glasses in 3dimensions, recent theoretical studies have proposed that Tc is zero in Heisenberg spin glasses and that the finite Tc of real systems is induced by the anisotropy. To clear up this question, we analyse the influence of the anisotropy on the critical behaviour and the transition temperature o...
A first-principles approach to the construction of concentration-temperature magnetic phase diagrams of metallic alloys is presented. The method employs self-consistent total energy calculations based on the coherent potential approximation for partially ordered and noncollinear magnetic states and is able to account for competing interactions and multiple magnetic phases. Application to the Fe...
Despite their importance in physics and chemistry, the origin and extent of the scaling relations between the energetics of adsorbed species on surfaces remain elusive. We demonstrate here that scalability is not exclusive to adsorbed atoms and their hydrogenated species but rather a general phenomenon between any set of adsorbates bound similarly to the surface. On the example of the near-surf...
2014 Measurements of the hysteresis cycle of the magnetization of CuMn 1 % in the spin glass state as a function of the concentration of a non magnetic impurity show that the width of the hysteresis is proportional to the concentration of Au at a rate of 6.2 ± 0.4 kOe/at. % Au. A much smaller rate observed for Al and Ag and higher rate observed for Pt demonstrate unambiguously that the spin orb...
A preliminary X-ray study of CaPtAl has been reported previously by Hulliger [J. Alloys Compd (1993), 196, 225-228] based on X-ray powder diffraction data without structure refinement. With the present single-crystal X-ray study, we confirm the assignment of the TiNiSi type for CaPtAl, in a fully ordered inverse structure. All three atoms of the asymmetric unit have .m. site symmetry. The struc...
Low-platinum-content quaternary PtCuCoNi nanotubes with markedly enhanced oxygen reduction activity.
Polymer electrolyte membrane fuel cells (PEMFCs), among other clean energy sources, represent a highly efficient and potentially inexpensive solution for worldwide ever-growing energy demand and increasing environmental concern, and are expected to be able to find various applications ranging from automotive vehicles to stationary and portable devices. Presently, the widespread commercializatio...
The influence of the electronic structure and the lattice constant on hydrogen absorption in bulk Pd3M1 (M = Cd, Ag, Au, Pd, Cu, Ni, Pt, Pb, Sn, Fe, Rh, Ru) has been studied by density-functional calculations. We have assumed face-centred cubic structure for all the alloys, and hydrogen has been placed in the octahedral site surrounded by six Pd atoms. We have calculated the absorption energy o...
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