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Full-Text Articles in Physics
Spin-Modified Catalysis, R Choudhary, Priyanka Manchanda, Axel Enders, Balamurugan Balamurugan, Arti Kashyap, David J. Sellmyer, Ralph A. Skomski
Spin-Modified Catalysis, R Choudhary, Priyanka Manchanda, Axel Enders, Balamurugan Balamurugan, Arti Kashyap, David J. Sellmyer, Ralph A. Skomski
Ralph Skomski Publications
First-principle calculations are used to explore the use of magnetic degrees of freedom in catalysis. We use the Vienna Ab-Initio Simulation Package to investigate both L10-ordered FePt and CoPt bulk materials and perform supercell calculations for FePt nanoclusters containing 43 atoms. As the catalytic activity of transition-metal elements and alloys involves individual d levels, magnetic alloying strongly affects the catalytic performance, because it leads to shifts in the local densities of states and to additional peaks due to magnetic-moment formation. The peak shift persists in nanoparticles but is surface-site specific and therefore depends on cluster size. Our research indicates that …
Correlations In Rare-Earth Transition-Metal Permanent Magnets, Ralph Skomski, Priyanka Manchanda, Arti Kashyap
Correlations In Rare-Earth Transition-Metal Permanent Magnets, Ralph Skomski, Priyanka Manchanda, Arti Kashyap
Ralph Skomski Publications
It is investigated how electron-electron correlations affect the intrinsic properties of rare-earth transition- metal magnets. Focusing on orbital moment and anisotropy, we perform model calculations for 3d-4f alloys and density-functional theory (DFT) calculations for NdCo5. On an independentelectron level, the use of a single Slater determinant with broken spin symmetry introduces Hund’s rule correlations, which govern the behavior of rare-earth ions and of alloys described by the local spin density approximation (LSDA) and LSDAþU approximations to DFT. By contrast, rareearth ions in intermetallics involve configuration interactions between two or more Slater determinants and lead to phenomena such as spin-charge distribution. …
Intrinsic Magnetic Properties Of L10 Feni Obtained From Meteorite Nwa 6259, Eric Poirier, Frederick E. Pinkerton, Robert Kubic, Raja K. Mishra, Nina Bordeaux, Arif Mubarok, Laura H. Lewis, Joseph I. Goldstein, Ralph Skomski, Katayun Barmak
Intrinsic Magnetic Properties Of L10 Feni Obtained From Meteorite Nwa 6259, Eric Poirier, Frederick E. Pinkerton, Robert Kubic, Raja K. Mishra, Nina Bordeaux, Arif Mubarok, Laura H. Lewis, Joseph I. Goldstein, Ralph Skomski, Katayun Barmak
Ralph Skomski Publications
FeNi having the tetragonal L10 crystal structure is a promising new rare-earth-free permanent magnet material. Laboratory synthesis is challenging, however, tetragonal L10 FeNi—the mineral “tetrataenite”—has been characterized using specimens found in nickel-iron meteorites. Most notably, the meteorite NWA 6259 recovered from Northwest Africa is 95 vol.% tetrataenite with a composition of 43 at.% Ni. Hysteresis loops were measured as a function of sample orientation on a specimen cut from NWA 6259 in order to rigorously deduce the intrinsic hard magnetic properties of its L10 phase. Electron backscatter diffraction showed that NWA 6259 is strongly textured, containing L10 grains oriented along …