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Iowa State University

2001

Series

Metallurgy

Articles 1 - 3 of 3

Full-Text Articles in Physics

Absence Of Fine Structure In The Photoemission Spectrum Of The Icosahedral Al-Pd-Mn Quasicrystal, Z. M. Stadnik, D. Purdie, Y. Baer, Thomas A. Lograsso Nov 2001

Absence Of Fine Structure In The Photoemission Spectrum Of The Icosahedral Al-Pd-Mn Quasicrystal, Z. M. Stadnik, D. Purdie, Y. Baer, Thomas A. Lograsso

Ames Laboratory Publications

The results of the low-temperature ultrahigh-energy-resolution photoemission studies of a single-grain icosahedral alloy Al70Pd21.5Mn8.5 have been presented. The existence of the theoretically predicted pseudogap in the density of states at the Fermi energy has been confirmed. No evidence of the theoretically predicted spikiness of the density of states could be observed. It has been suggested that the failure to detect the predicted spikiness of the density of states in icosahedral quasicrystals is consistent with the results of Zijlstra and Janssen [Europhys. Lett. 52, 578 (2000)] who showed that the spikiness occurs only in ...


Phonon Softening In Ni-Mn-Ga Alloys, Lluís Mañosa, Antoni Planes, Jerel L. Zarestky, Thomas A. Lograsso, Deborah L. Schlagel, C. Stassis Jun 2001

Phonon Softening In Ni-Mn-Ga Alloys, Lluís Mañosa, Antoni Planes, Jerel L. Zarestky, Thomas A. Lograsso, Deborah L. Schlagel, C. Stassis

Ames Laboratory Publications

The TA2 phonon dispersion curves of Ni-Mn-Ga alloys with different compositions which transform to different martensitic structures have been measured over a broad temperature range covering both paramagnetic and ferromagnetic phases. The branches show an anomaly (dip) at a wave number that depends on the particular martensitic structure, and there is softening of these anomalous phonons with decreasing temperature. This softening is enhanced below the Curie point, as a consequence of spin-phonon coupling. This effect is stronger for systems with higher electronic concentration.


Physical Properties Of Heusler-Like Fe2val, Ye Feng, J. Y. Rhee, T. A. Wiener, David W. Lynch, B. E. Hubbard, A. J. Sievers, Deborah L. Schlagel, Thomas A. Lograsso, L. L. Miller Apr 2001

Physical Properties Of Heusler-Like Fe2val, Ye Feng, J. Y. Rhee, T. A. Wiener, David W. Lynch, B. E. Hubbard, A. J. Sievers, Deborah L. Schlagel, Thomas A. Lograsso, L. L. Miller

Ames Laboratory Publications

A comprehensive characterization of the compound Fe2VAl was carried out. Samples grown by arc melting or the Bridgman method have Al and Fe deficiencies of up to 5 at. %. Czochralski-grown samples were Fe rich and Al deficient. X-ray diffraction implies appreciable antisite disorder in all of our samples. Fourier-transform infrared (FTIR) spectroscopy measurements showed that the carrier density and scattering time had little sample-to-sample variation or temperature dependence for near-stoichiometric samples. FTIR and dc resistivity suggest that the transport properties of Fe2VAl are influenced by both localized and delocalized carriers, with the former primarily responsible for ...