The interplay of long-range magnetic order and single-ion anisotropy in rare earth nickel germanides

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This dissertation is concerned with the interplay of long-range order and anisotropy in the tetragonal RNi{sub 2}Ge{sub 2} (R = rare earth) family of compounds. Microscopic magnetic structures were studied using both neutron and x-ray resonant exchange scattering (XRES) techniques. The magnetic structures of Tb, Dy, Eu and Gd members have been determined using high-quality single-crystal samples. This work has correlated a strong Fermi surface nesting to the magnetic ordering in the RNi{sub 2}Ge{sub 2} compounds. Generalized susceptibility, {chi}{sub 0}(q), calculations found nesting to be responsible for both incommensurate ordering wave vector in GdNi{sub 2}Ge{sub 2}, and the commensurate structure ... continued below

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165 p.

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Islam, Z. May 10, 1999.

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  • Ames Laboratory
    Publisher Info: Ames Lab., IA (United States)
    Place of Publication: Iowa

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Description

This dissertation is concerned with the interplay of long-range order and anisotropy in the tetragonal RNi{sub 2}Ge{sub 2} (R = rare earth) family of compounds. Microscopic magnetic structures were studied using both neutron and x-ray resonant exchange scattering (XRES) techniques. The magnetic structures of Tb, Dy, Eu and Gd members have been determined using high-quality single-crystal samples. This work has correlated a strong Fermi surface nesting to the magnetic ordering in the RNi{sub 2}Ge{sub 2} compounds. Generalized susceptibility, {chi}{sub 0}(q), calculations found nesting to be responsible for both incommensurate ordering wave vector in GdNi{sub 2}Ge{sub 2}, and the commensurate structure in EuNi{sub 2}Ge{sub 2}. A continuous transition from incommensurate to commensurate magnetic structures via band filling is predicted. The surprisingly higher T{sub N} in EuNi{sub 2}Ge{sub 2} than that in GdNi{sub 2}Ge{sub 2} is also explained. Next, all the metamagnetic phases in TbNi{sub 2}Ge{sub 2} with an applied field along the c axis have been characterized with neutron diffraction measurements. A mixed phase model for the first metamagnetic structure consisting of fully-saturated as well as reduced-moment Tb ions is presented. The moment reduction may be due to moment instability which is possible if the exchange is comparable to the low-lying CEF level splitting and the ground state is a singlet. In such a case, certain Tb sites may experience a local field below the critical value needed to reach saturation.

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165 p.

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INIS; OSTI as DE99003353

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  • Other Information: TH: Thesis (Ph.D.)

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  • Other: DE99003353
  • Report No.: IS-T--1870
  • Grant Number: W-7405-ENG-82
  • DOI: 10.2172/354997 | External Link
  • Office of Scientific & Technical Information Report Number: 354997
  • Archival Resource Key: ark:/67531/metadc686054

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  • May 10, 1999

Added to The UNT Digital Library

  • July 25, 2015, 2:20 a.m.

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  • Nov. 6, 2015, 8:46 p.m.

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Islam, Z. The interplay of long-range magnetic order and single-ion anisotropy in rare earth nickel germanides, report, May 10, 1999; Iowa. (digital.library.unt.edu/ark:/67531/metadc686054/: accessed September 21, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.