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Title: Magnetic ordering in the rare earth iron germanates HoFeGe{sub 2}O{sub 7} and ErFeGe{sub 2}O{sub 7}

Abstract

RFeGe{sub 2}O{sub 7} (R = Ho, Er) have been prepared in polycrystalline form, and their crystal structures have been refined from room-temperature high-resolution neutron diffraction data by the Rietveld method. Both materials are isostructural, space group P2{sup 1}/m (no. 11), Z = 4. The most interesting feature of the structure is the existence of flattened chains of RO{sub 7} polyhedra along the b axis, which linked in the c direction through pairs of FeO{sub 6} octahedra form layers parallel to the bc crystal plane. Magnetic susceptibility measurements between 350 and 1.7 K reveal the existence of two anomalies for both compounds, at T{sub 1} and T{sub 2}, (T{sub 2} < T{sub 1}), 39 and 12 K, 40 and 8 K, for R = Ho and Er, respectively. From low-temperature neutron diffraction data, three-dimensional antiferromagnetic ordering in both compounds is established, with a simultaneous setting up of the order for R{sup 3+} and Fe{sup 3+} sublattices at T{sub N} = T{sub 1}. The propagation vector of the magnetic structure is k = [0, 0, 0]. In each case the magnetic structure consists of a ferromagnetic arrangement of all R{sup 3+} and Fe{sup 3+} magnetic moments within one ac plane, whereas themore » corresponding moments in up and down adjacent planes are oppositely aligned, leading to 3D AF coupling along the b direction. Kramers doublets splitting in the region of the {sup 4}I{sub 15/2}{r{underscore}arrow}{sup 4}I{sub 13/2} optical transitions of the Er compound have been observed in high-resolution optical absorption spectra. From these spectral measurements the temperature found for the magnetic ordering coincides with that T{sub N} determined by neutron diffraction data. Moreover optical data also show that T{sub 2} in {chi}{sub m}(T) does not correspond to any phase transition but it is most probably caused by the population changes within the ground Er{sup 3+} Kramers doublet split by the exchange interaction with the ordered Fe{sup 3+} subsystem.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Inst. de Ciencia de Materiales de Madrid (ES)
OSTI Identifier:
20001173
Resource Type:
Journal Article
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 11; Journal Issue: 9; Other Information: PBD: Sep 1999; Journal ID: ISSN 0897-4756
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; GERMANIUM OXIDES; IRON OXIDES; HOLMIUM OXIDES; ERBIUM OXIDES; MAGNETIC SUSCEPTIBILITY; CRYSTAL STRUCTURE

Citation Formats

Cascales, C., Puebla, E.G., Klimin, S., Lebech, B., Monge, A., and Popova, M.N. Magnetic ordering in the rare earth iron germanates HoFeGe{sub 2}O{sub 7} and ErFeGe{sub 2}O{sub 7}. United States: N. p., 1999. Web. doi:10.1021/cm991053m.
Cascales, C., Puebla, E.G., Klimin, S., Lebech, B., Monge, A., & Popova, M.N. Magnetic ordering in the rare earth iron germanates HoFeGe{sub 2}O{sub 7} and ErFeGe{sub 2}O{sub 7}. United States. doi:10.1021/cm991053m.
Cascales, C., Puebla, E.G., Klimin, S., Lebech, B., Monge, A., and Popova, M.N. Wed . "Magnetic ordering in the rare earth iron germanates HoFeGe{sub 2}O{sub 7} and ErFeGe{sub 2}O{sub 7}". United States. doi:10.1021/cm991053m.
@article{osti_20001173,
title = {Magnetic ordering in the rare earth iron germanates HoFeGe{sub 2}O{sub 7} and ErFeGe{sub 2}O{sub 7}},
author = {Cascales, C. and Puebla, E.G. and Klimin, S. and Lebech, B. and Monge, A. and Popova, M.N.},
abstractNote = {RFeGe{sub 2}O{sub 7} (R = Ho, Er) have been prepared in polycrystalline form, and their crystal structures have been refined from room-temperature high-resolution neutron diffraction data by the Rietveld method. Both materials are isostructural, space group P2{sup 1}/m (no. 11), Z = 4. The most interesting feature of the structure is the existence of flattened chains of RO{sub 7} polyhedra along the b axis, which linked in the c direction through pairs of FeO{sub 6} octahedra form layers parallel to the bc crystal plane. Magnetic susceptibility measurements between 350 and 1.7 K reveal the existence of two anomalies for both compounds, at T{sub 1} and T{sub 2}, (T{sub 2} < T{sub 1}), 39 and 12 K, 40 and 8 K, for R = Ho and Er, respectively. From low-temperature neutron diffraction data, three-dimensional antiferromagnetic ordering in both compounds is established, with a simultaneous setting up of the order for R{sup 3+} and Fe{sup 3+} sublattices at T{sub N} = T{sub 1}. The propagation vector of the magnetic structure is k = [0, 0, 0]. In each case the magnetic structure consists of a ferromagnetic arrangement of all R{sup 3+} and Fe{sup 3+} magnetic moments within one ac plane, whereas the corresponding moments in up and down adjacent planes are oppositely aligned, leading to 3D AF coupling along the b direction. Kramers doublets splitting in the region of the {sup 4}I{sub 15/2}{r{underscore}arrow}{sup 4}I{sub 13/2} optical transitions of the Er compound have been observed in high-resolution optical absorption spectra. From these spectral measurements the temperature found for the magnetic ordering coincides with that T{sub N} determined by neutron diffraction data. Moreover optical data also show that T{sub 2} in {chi}{sub m}(T) does not correspond to any phase transition but it is most probably caused by the population changes within the ground Er{sup 3+} Kramers doublet split by the exchange interaction with the ordered Fe{sup 3+} subsystem.},
doi = {10.1021/cm991053m},
journal = {Chemistry of Materials},
issn = {0897-4756},
number = 9,
volume = 11,
place = {United States},
year = {1999},
month = {9}
}