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Iowa State University

Series

Metallurgy

Physics and Astronomy

2004

Articles 1 - 4 of 4

Full-Text Articles in Physics

Elastic Constants Of Ni-Mn-Ga Magnetic Shape Memory Alloys, Marcelo Stipcich, Lluís Mañosa, Antoni Planes, Michel Morin, Jerel L. Zarestky, Thomas A. Lograsso, C. Stassis Aug 2004

Elastic Constants Of Ni-Mn-Ga Magnetic Shape Memory Alloys, Marcelo Stipcich, Lluís Mañosa, Antoni Planes, Michel Morin, Jerel L. Zarestky, Thomas A. Lograsso, C. Stassis

Ames Laboratory Publications

We have measured the adiabatic second order elastic constants of two Ni-Mn-Ga magnetic shape memory crystals with different martensitic transition temperatures, using ultrasonic methods. The temperature dependence of the elastic constants has been followed across the ferromagnetic transition and down to the martensitic transition temperature. Within experimental errors no noticeable change in any of the elastic constants has been observed at the Curie point. The temperature dependence of the shear elastic constant C′ has been found to be very different for the two alloys. Such a different behavior is in agreement with recent theoretical predictions for systems undergoing multi-stage structural ...


Electrical Transport In Amorphous Semiconducting Almgb14 Films, Y. Tian, G. Li, Joseph Shinar, N. L. Wang, Bruce A. Cook, James W. Anderegg, Alan P. Constant, Alan Mark Russell, J. E. Snyder Aug 2004

Electrical Transport In Amorphous Semiconducting Almgb14 Films, Y. Tian, G. Li, Joseph Shinar, N. L. Wang, Bruce A. Cook, James W. Anderegg, Alan P. Constant, Alan Mark Russell, J. E. Snyder

Materials Science and Engineering Publications

The electrical transport properties of semiconducting AlMgB14films deposited at room temperature and 573K are reported in this letter. The as-deposited films are amorphous, and they exhibit high n-type electrical conductivity, which is believed to stem from the conduction electrons donated by Al, Mg, and/or Fe impurities in these films. The film deposited at 573K is less conductive than the room-temperature-deposited film. This is attributed to the nature of donor or trap states in the band gap related to the different deposition temperatures.


Reversible Spin-Flop And Irreversible Metamagneticlike Transitions Induced By A Magnetic Field In The Layered Gd5ge4 Antiferromagnet, Evgenii M. Levin, Karl A. Gschneidner Jr., Thomas A. Lograsso, Deborah L. Schlagel, Vitalij K. Pecharsky Apr 2004

Reversible Spin-Flop And Irreversible Metamagneticlike Transitions Induced By A Magnetic Field In The Layered Gd5ge4 Antiferromagnet, Evgenii M. Levin, Karl A. Gschneidner Jr., Thomas A. Lograsso, Deborah L. Schlagel, Vitalij K. Pecharsky

Ames Laboratory Publications

Temperature and magnetic field dependencies of the magnetization of single crystal Gd5Ge4 indicate antiferromagnetic coupling along the c direction below 130 K. Both a reversible spin-flop transition when a magnetic field of ∼8.4kOe is applied along the cdirection, and irreversible metamagneticlike transitions when a 20 kOe or greater magnetic field is applied at 4.3 K along any of the three crystallographic axes are observed. Although Gd3+ ions have negligible single ion anisotropy, the metamagnetic transitions and magnetization of Gd5Ge4 in the ferromagnetic state depend on the crystallographic direction reflecting the anisotropy of ...


Reflectance Anisotropy Of Gd5si2ge2 And Tb5si2.2ge1.8, S. J. Lee, Joong Mok Park, J. E. Snyder, David C. Jiles, Deborah L. Schlagel, Thomas A. Lograsso, A. O. Pecharsky, David W. Lynch Mar 2004

Reflectance Anisotropy Of Gd5si2ge2 And Tb5si2.2ge1.8, S. J. Lee, Joong Mok Park, J. E. Snyder, David C. Jiles, Deborah L. Schlagel, Thomas A. Lograsso, A. O. Pecharsky, David W. Lynch

Ames Laboratory Publications

Reflectance difference (RD) spectra for the ab plane of the single crystals of Gd5Si2Ge2and bc planes of Gd5Si2Ge2 and Tb5Si2.2Ge1.8 were obtained in the photon energy range of 1.5–5.5 eV. Several peaks were observed for these crystals in the measured spectrum range. Similar features were observed in the RD spectra for the bc planes ofGd5Si2Ge2 and Tb5Si2.2Ge1.8, while different features were observed for the ...