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Series

1984

David Sellmyer Publications

Articles 1 - 6 of 6

Full-Text Articles in Physics

Rare-Earth—Gallium—Iron Glasses. I. Magnetic Ordering And Hysteresis In Alloys Based On Gd, Tb, And Er , S.G. Cornelison, David J. Sellmyer Sep 1984

Rare-Earth—Gallium—Iron Glasses. I. Magnetic Ordering And Hysteresis In Alloys Based On Gd, Tb, And Er , S.G. Cornelison, David J. Sellmyer

David Sellmyer Publications

Results of magnetic measurements are presented on the new metallic glass systems (R80Ga20)100-xFex and (R80Ga20)90B10, where R denotes the heavy rare earths Gd, Tb, and Er, for x=10, 20, and 30, respectively. High-field magnetization (to 80 kOe) and ac and dc susceptibility measurements were made from 1.4 to 300 K. The Gd-Fe glasses are simple ferrimagnets with opposing Gd and Fe moments. The Gd-B glass exhibits two apparent transitions (paramagnetic—ferromagnetic—like, and ferromagnetic spin-glass) as the temperature is lowered. As Fe is added, the low-temperature ...


Magnetic Properties And Chemical Short-Range Order In Fe-Pd-Based Metallic Glasses , J.G. Zhao, David J. Sellmyer Sep 1984

Magnetic Properties And Chemical Short-Range Order In Fe-Pd-Based Metallic Glasses , J.G. Zhao, David J. Sellmyer

David Sellmyer Publications

High-field magnetization and ac susceptibility measurements are reported on a series of FexPd80-xSi10B10 rapidly quenched alloys for 0<~x<~80. X-ray diffraction data show that these alloys are amorphous up to at least x=40 and that the x=60 and 80 samples are partially crystalline. The ac susceptibility data can be interpreted in terms of ferromagnetic, spin-glass, and double transitions, and a qualitative magnetic phase diagram of the system is obtained. The concentration dependence of the saturation magnetization, as well as the magnetic phase diagram, exhibits sharp anomalies at about x=13. These data suggest the presence of chemical short-range order for x≳13. X-ray photoelectron and Mössbauer results are consistent with this model.


Rare-Earth—Gallium—Iron Glasses. Ii. Anomalous Magnetic Hysteresis In Alloys Based On Pr, Nd, And Sm , S.G. Cornelison, J.G. Zhao, David J. Sellmyer Sep 1984

Rare-Earth—Gallium—Iron Glasses. Ii. Anomalous Magnetic Hysteresis In Alloys Based On Pr, Nd, And Sm , S.G. Cornelison, J.G. Zhao, David J. Sellmyer

David Sellmyer Publications

Giant magnetic coercivity is reported in several metallic glasses of the form (R80G20)100-xFex where R represents Pr, Nd, or Sm, G represents Ga or Au, and 15≤x≤30. An unusual temperature variation of the coercive field is observed showing peaks at intermediate temperatures (≃90 K). In contrast to similar glasses based on heavy rare-earth metals, these glasses exhibit significant chemical short-range order and even phase separation as is shown by the Mössbauer effect and other measurements. The results are consistent with a recent theory which predicts that large coercivity can result from the ...


Temperature-Dependent Resistivity Of Highly Disordered Ni-Cr-Al Alloys , R. Hight, C. Plough, David J. Sellmyer May 1984

Temperature-Dependent Resistivity Of Highly Disordered Ni-Cr-Al Alloys , R. Hight, C. Plough, David J. Sellmyer

David Sellmyer Publications

Measurements are reported on the electrical resistivity of highly disordered Ni-Cr-Al films between 4.2 and 300 K. X-ray diffraction measurements show the films to be crystalline with a bcc structure. Negative temperature coefficients are observed and the resistivity data above about 50 K can be fitted by the expression ρ(T)=ρ0 [1-cln(T22)], where Δ depends on the heat treatment of the sample.


Magnetic Hardening In Rapidly Quenched Fe-Pr And Fe-Nd Alloys, David J. Sellmyer, A. Ahmed, G. Muench, George C. Hadjipanayis Mar 1984

Magnetic Hardening In Rapidly Quenched Fe-Pr And Fe-Nd Alloys, David J. Sellmyer, A. Ahmed, G. Muench, George C. Hadjipanayis

David Sellmyer Publications

We report studies of high-field magnetization and thermomagnetic effects in rapidly quenched and heat treated alloys based on Fe-Pr and Fe-Nd. Coercivities up to ~40 kOe and large energy products result from the precipitation of a finely dispersed crystalline phase. Studies of varying the alloy composition and heat treatment are reported. Journal of Applied Physics is copyrighted by The American Institute of Physics.


Spin-Glass-Like Freezing In Disordered Mnpd3 And Crpd3 Alloys, M.H. Rashid, David J. Sellmyer Mar 1984

Spin-Glass-Like Freezing In Disordered Mnpd3 And Crpd3 Alloys, M.H. Rashid, David J. Sellmyer

David Sellmyer Publications

We report studies of dc and ac susceptibility and high-field magnetization on disordered samples of MnPd3 and CrPd3. Both samples undergo spin-glass-like transitions, as is evident from susceptibility peaks at 45 and 37 K, respectively. The effective paramagnetic moments deduced from Curie–Weiss fits of the susceptibility in the paramagnetic region are 0.38µB/Mn and 0.4µB/Cr. Both materials show saturation effects at high applied fields and a flat χ(T) below the spin-freezing temperature in the field-cooled state. The data are discussed in terms of a cluster-glass model with local antiferromagnetic interactions. Journal ...