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Magnetic susceptibility of AnRe/sub 2/ compounds

Description: The compounds AnRe/sub 2/, where An = Th, U, Np, and Pu all have the MgZn/sub 2/-type hexagonal Laves phase structure. Measurements of their magnetic susceptibilities have been made from 2-300 K. Whereas ThRe/sub 2/, URe/sub 2/, and PuRe/sub 2/ have essentially temperature-independent susceptibilities, NpRe/sub 2/ is ferromagnetic with T/sub c/ = 47 K. The paramagnetic data for NpRe/sub 2/ follow a modified Curie-Weiss law, chi-che/sub 0/ = C/(T-THETA) from 60-230 K with THETA = 46.9 K and C eq… more
Date: January 1, 1977
Creator: Brodsky, M. B.; Trainor, R. J.; Aldred, A. T. & Sowers, C. H.
Partner: UNT Libraries Government Documents Department
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Epitaxial growth of bcc transition metal films and superlattices onto MgO (111), (011) and (001) substrates

Description: We demonstrate epitaxial growth of the bcc transition metals Nb, Mo, Fe, and Cr via sputtering onto single crystal MgO substrates. The epitaxial growth orientations are (011), (112) and (001) when grown onto MgO (111), (011) and (001), respectively. Further we demonstrate that under appropriate growth conditions, superlattices of these materials (e.g., Fe/Cr, Fe/V and Mo/V) can be grown with the same epitaxial order as the films.
Date: April 1, 1994
Creator: Mattson, J. E.; Fullerton, E. E.; Sowers, C. H. & Bader, S. D.
Partner: UNT Libraries Government Documents Department
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Growth of oriented rare-earth-transition-metal thin films

Description: Rare-earth-transition-metal thin films are successfully grown by magnetron sputtering onto single-crystal MgO substrates with epitaxial W buffer layers. The use of epitaxial W buffer layers allows oriented single-phase films to be grown. Sm-Co films grown onto W(100), have strong in-plane anisotropy and coercivities exceeding 5 T at 5 K whereas Fe-Sm films have strong perpendicular anisotropy and are magnetically soft.
Date: April 1, 1996
Creator: Fullerton, Eric E.; Sowers, C. H.; Bader, S. D. & Wu, X. Z.
Partner: UNT Libraries Government Documents Department
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Exchange-spring behavior in epitaxial hard/soft magnetic bilayer films.

Description: We present results on the magnetic reversal process in epitaxial Sm-Co (1{bar 1}00)/TM (TM = Fe, Co) bilayer films prepared via magnetron sputtering onto Cr-buffered single-crystal MgO substrates. The magnetically hard Sm-Co films have 20-T uniaxial anisotropy and coercivities >3 T at room temperature. The magnetization of the soft layer is pinned at the interface to the hard-magnet layer and switches reversibly as expected for an exchange-spring magnet. With increasing soft layer thickness,… more
Date: December 5, 1997
Creator: Bader, S. D.; Fullerton, E. E.; Grimsditch, M.; Jiang, J. S. & Sowers, C. H.
Partner: UNT Libraries Government Documents Department
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Magnetic phase transitions in epitaxial Fe/Cr superlattices

Description: The surface spin-flop and Neel transitions are examined in Fe/Cr superlattices. The surface spin-flop, originally predicted by Mills [Phys. Rev. Lett. 20, 18 (1968)], is observed in Fe/Cr(211) superlattices with antiferromagnetic interlayer coupling and uniaxial in-plane-anisotropy. The Neel transition (T{sub N}) of Cr is observed in Fe/Cr(001) superlattices, for which the onset of antiferromagnetism is at a thickness t{sub Cr} of 42{angstrom}. The bulk value of T{sub N} is approached asymptoti… more
Date: December 31, 1995
Creator: Fullerton, Eric E.; Sowers, C. H.; Bader, S. D.; Riggs, K. T. & Berger, A.
Partner: UNT Libraries Government Documents Department
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Neutron-induced collision cascade mixing in Nb/V superlattices

Description: High-angle X-ray diffraction was used to determine cascade mixing efficiencies, Dt/dpa, in Nb/V superlattices irradiated to small doses ({le}0.26 dpa). Samples were neutron irradiated in the core of the High Flux Beam Reactor at Brookhaven National Laboratory and ion irradiated with 1.5 MeV Ne. No significant differences were observed in cascade mixing efficiencies between the two types of irradiation. Values of Dt/dpa were observed to vary with the modulation wavelength of the superlattice, wi… more
Date: July 1, 1993
Creator: Alexander, D. E.; Fullerton, E. E.; Baldo, P. M.; Sowers, C. H. & Rehn, L. E.
Partner: UNT Libraries Government Documents Department
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Modulation wavelength dependence of ion mixing in metallic superlattices

Description: Ion mixing was studied in polycrystalline Nb/V and single-crystal Mo/V superlattices and in bilayers of the same materials. Systematic variation in the modulation wavelength, {Lambda}, revealed a factor of three decrease in mixing efficiency at small {Lambda} for Nb/V. The decrease appears to coincide with a structural transition in which the Nb/V superlattices become coherent. The results are consistent with a diffusion-induced grain boundary migration interpretation of mixing during irradiati… more
Date: November 1, 1993
Creator: Alexander, D. E.; Fullerton, E. E.; Baldo, P. M.; Sowers, C. H. & Rehn, L. E.
Partner: UNT Libraries Government Documents Department
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Structure and magnetism of epitaxial rare-earth-transition-metal films

Description: Growth of epitaxial transition-metal superlattices; has proven essential in elucidating the role of crystal orientation and structure on magnetic properties such as giant magnetoresistance, interlayer coupling, and magnetic surface anisotropies. Extending these studies to the growth of epitaxial rare earth-transition metal (RE-TM) films and superlattices promises to play an equally important role in exploring and optimizing the properties of hard magnets. For instance, Skomski and Coey predict … more
Date: October 1, 1996
Creator: Fullerton, E. E.; Sowers, C. H.; Pearson, J. P. & Bader, S. D.
Partner: UNT Libraries Government Documents Department
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Search for coupling in ferromagnetic/superconducting multilayers: Fe{sub 4}N/NbN

Description: Structural, magnetic and superconducting properties of ferromagnetic/superconducting multilayers of Fe{sub 4}N/NbN are examined. The onset of superconductivity occurs at a NbN layer thickness of {approximately}100{Angstrom}. Below this thickness ferromagnetism of the Fe{sub 4}N layers is observed. Above this thickness superconductivity of the NbN is also observed, but there is no evidence for interlayer magnetic or superconductive coupling. The results are used in the formulation of guidelines … more
Date: November 1, 1996
Creator: Mattson, J. E.; Potter, C. D.; Conover, M. J.; Sowers, C. H. & Bader, S. D.
Partner: UNT Libraries Government Documents Department
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Interfacial structure of lattice mismatched bcc(110)/bcc(110) transition metal superlattices

Description: We present structural characterizations of a series of sputtered Fe/Nb and V/Nb superlattices by high-angle x-ray diffraction. Diffraction scans were performed with the scattering vector at various angles ({Chi}) with respect to the layers. {Chi}=0{degrees} diffraction spectra (normal to the layers) were fitted to a general structural model to determine the (110) lattice strains, interfacial disorder and interdiffusion. {Chi}>0{degrees} spectra probe the lattice strain of the individual layers … more
Date: March 1, 1993
Creator: Fullerton, E. E.; Sowers, C. H.; Bader, S. D.; Mini, S.; Bommannavar, A. S. & Ehrlich, S. N.
Partner: UNT Libraries Government Documents Department
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Magnetic and structural properties of Fe/Pd multilayers studied by magnetic x-ray dichroism and x-ray absorption spectroscopy

Description: The results of magnetic circular x-ray dichroism (MCXD) measurements and extended x-ray absorption fine structure measurements (EXAFS) of the Fe K-edges of textured Fe(110)/Pd(111) multilayers are reported. The EXAFS results indicates that the iron in the system goes from bcc to a more densely packed system as the thickness of the iron layer is decreased. The magnetic properties were measured by SQUID magnetometry from 5-350 K. For all the samples, the saturation magnetization was significantly… more
Date: December 1, 1994
Creator: Mini, S. M.; Fullerton, E. E.; Sowers, C. H.; Fontaine, A.; Pizzini, S.; Bommannavar, A. S. et al.
Partner: UNT Libraries Government Documents Department
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Oscillatory interlayer magnetic coupling of sputtered Fe/Nb superlattices

Description: The saturation field of sputtered Fe/Nb superlattices oscillates as a function of the Nb thickness with a periodicity of {approximately}9 {Angstrom}. In contrast to the case of Fe/Cr superlattices, the concurrent magnetoresistance oscillations were found to be very weak. Yet polarized neutron reflection measurements confirm that the Fe/Nb superlattices with high saturation field possess a magnetic ground state of the {plus_minus}{plus_minus} type. Neutron and x-ray measurements indicate that, w… more
Date: September 1, 1992
Creator: Mattson, J. E.; Fullerton, E. E.; Sowers, C. H.; Huang, Y. Y.; Felcher, G. P. & Bader, S. D.
Partner: UNT Libraries Government Documents Department
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Oscillatory interlayer magnetic coupling of sputtered Fe/Nb superlattices

Description: The saturation field of sputtered Fe/Nb superlattices oscillates as a function of the Nb thickness with a periodicity of [approximately]9 [Angstrom]. In contrast to the case of Fe/Cr superlattices, the concurrent magnetoresistance oscillations were found to be very weak. Yet polarized neutron reflection measurements confirm that the Fe/Nb superlattices with high saturation field possess a magnetic ground state of the [plus minus][plus minus] type. Neutron and x-ray measurements indicate that, w… more
Date: September 1, 1992
Creator: Mattson, J. E.; Fullerton, E. E.; Sowers, C. H.; Huang, Y. Y.; Felcher, G. P. & Bader, S. D.
Partner: UNT Libraries Government Documents Department
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Spring magnet films.

Description: The properties of exchange-spring-coupled bilayer and superlattice films are highlighted for Sm-Co hard magnet and Fe or Co soft magnet layers. The hexagonal Sm-Co is grown via magnetron sputtering in a- and b-axis epitaxial orientations. In both cases the c-axis, in the film plane, is the easy axis of magnetization. Trends in coercivity with film thickness are established and related to the respective microstructure of the two orientations. The magnetization reversal process for the bilayers i… more
Date: March 29, 1999
Creator: Bader, S. D.; Fullerton, E. E.; Gornakov, V. S.; Inomata, A.; Jiang, J. S.; Nikitenko, V. I. et al.
Partner: UNT Libraries Government Documents Department
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Photo- and thermal-induced antiferromagnetic interlayer coupling in Fe/(Fe-Si) superlattices

Description: We have grown via sputtering, Fe - iron silicide superlattices that exhibit novel thermal and photomagnetic effects. For {approximately}15 {Angstrom} nominal thickness of the silicide layer the superlattices are antiferromagnetically (AF) coupled at room temperature. Upon cooling below 100K, they gradually revert to ferromagnetic alignment, but the AF coupling is restored at low temperature by exposure to visible light off sufficient intensity (> 10 mW/mm{sup 2}). These effects are due to charg… more
Date: August 1, 1993
Creator: Mattson, J. E.; Fullerton, E. E.; Kumar, S.; Lee, S. R.; Sowers, C. H.; Grimsditch, M. et al.
Partner: UNT Libraries Government Documents Department
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Non-oscillatory antiferromagnetic coupling in sputtered Fe/Si superlattices

Description: A series of sputtered Fe(30{Angstrom})/Si(x) superlattices were grown for x=10--40{Angstrom}. Magnetization and Kerr hysteresis loops, and neutron-reflectively measurements identify antiferromagnetic (AF) coupling of the Fe layers at room temperature for x=15{Angstrom} nominal thickness, with switching fields of 6kOe. X-ray structural analysis indicate that the spacer medium is crystalline for x<20{Angstrom}, while sputtered Si is amorphous (a). Failure to detect oscillations in the AF coupling… more
Date: June 1, 1992
Creator: Fullerton, E. E.; Mattson, J. E.; Lee, S. R.; Sowers, C. H.; Huang, Y. Y.; Felcher, G. et al.
Partner: UNT Libraries Government Documents Department
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Magnetic decoupling in sputtered Fe/Si superlattices and multilayers

Description: A series of sputtered Fe/Si superlattices was grown to study the magnetic coupling between ferromagnetic Fe layers (30{Angstrom} thick) for Si spacer-layer thicknesses (t{sub Si}) between 10 and 40{Angstrom}. The material is ferromagnetically coupled for t{sub Si}<13{Angstrom} and antiferromagneticly coupled for 13{Angstrom}<t{sub Si}<17{Angstrom}. For t{sub Si}>17{Angstrom} the magnetic Fe layers are uncoupled. X-ray analysis indicates that the system is well layered, but that the crystal stru… more
Date: September 1, 1992
Creator: Fullerton, E. E.; Mattson, J. E.; Lee, S. R.; Sowers, C. H.; Huang, Y. Y.; Felcher, G. et al.
Partner: UNT Libraries Government Documents Department
open access

Magnetic decoupling in sputtered Fe/Si superlattices and multilayers

Description: A series of sputtered Fe/Si superlattices was grown to study the magnetic coupling between ferromagnetic Fe layers (30[Angstrom] thick) for Si spacer-layer thicknesses (t[sub Si]) between 10 and 40[Angstrom]. The material is ferromagnetically coupled for t[sub Si]<13[Angstrom] and antiferromagneticly coupled for 13[Angstrom]<t[sub Si]<17[Angstrom]. For t[sub Si]>17[Angstrom] the magnetic Fe layers are uncoupled. X-ray analysis indicates that the system is well layered, but that the crystal stru… more
Date: September 1, 1992
Creator: Fullerton, E. E.; Mattson, J. E.; Lee, S. R.; Sowers, C. H.; Huang, Y. Y.; Felcher, G. et al.
Partner: UNT Libraries Government Documents Department
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