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Title: Structure and magnetism in the Kagome antiferromagnet RBaCo{sub 4}O{sub 7}.

Abstract

The mixed-valent compound RBaCo4O7 (R=Rare earth, Y), hereafter abbreviated as R-114, is built up of Kagome sheets of CoO4 tetrahedra, linked in the third dimension by a triangular layer of CoO4 tetrahedra in an analogous fashion to that found in the known geometrically frustrated magnets such as pyrochlores and SrCr9xGa12-9xO19 (SCGO). We have undertaken a study of the structural and magnetic properties of the Y-114 and Yb-114 compound using combined high resolution powder neutron and synchrotron X-ray diffraction. Both compounds undergo a first order trigonal {yields} orthorhombic phase transition that breaks the trigonal symmetry of the structure. We show from Bond Valence Sum arguments that this transition occurs as a response to a markedly underbonded Ba2+ site in the high-temperature phase. The symmetry-lowering transition relieves the geometric frustration of the structure, and a long-range ordered 3-D antiferromagnetic state develops at low temperature. The magnetic structure of the Y compound has been solved and shows a compromise between the well-known 120o structure of the Kagome net and a collinear antiferromagnet in the third dimension.

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
971455
Report Number(s):
ANL/MSD/CP-58373
TRN: US1001203
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Conference
Resource Relation:
Conference: 2006 Materials Research Society Fall Meeting; Nov. 27, 2006 - Dec. 1, 2006; Boston, MA
Country of Publication:
United States
Language:
ENGLISH
Subject:
43 PARTICLE ACCELERATORS; DIMENSIONS; MAGNETIC PROPERTIES; MAGNETISM; MAGNETS; NEUTRONS; RESOLUTION; SYMMETRY; SYNCHROTRONS; VALENCE; X-RAY DIFFRACTION

Citation Formats

Mitchell, J. F., Zheng, H., Huq, A., Chapon, L. C., Radaelli, P. G., Stephens, P. W., Materials Science Division, ORNL, Rutherford Appleton Lab., and State Univ. of New York at Stonybrook. Structure and magnetism in the Kagome antiferromagnet RBaCo{sub 4}O{sub 7}.. United States: N. p., 2007. Web.
Mitchell, J. F., Zheng, H., Huq, A., Chapon, L. C., Radaelli, P. G., Stephens, P. W., Materials Science Division, ORNL, Rutherford Appleton Lab., & State Univ. of New York at Stonybrook. Structure and magnetism in the Kagome antiferromagnet RBaCo{sub 4}O{sub 7}.. United States.
Mitchell, J. F., Zheng, H., Huq, A., Chapon, L. C., Radaelli, P. G., Stephens, P. W., Materials Science Division, ORNL, Rutherford Appleton Lab., and State Univ. of New York at Stonybrook. Mon . "Structure and magnetism in the Kagome antiferromagnet RBaCo{sub 4}O{sub 7}.". United States. doi:.
@article{osti_971455,
title = {Structure and magnetism in the Kagome antiferromagnet RBaCo{sub 4}O{sub 7}.},
author = {Mitchell, J. F. and Zheng, H. and Huq, A. and Chapon, L. C. and Radaelli, P. G. and Stephens, P. W. and Materials Science Division and ORNL and Rutherford Appleton Lab. and State Univ. of New York at Stonybrook},
abstractNote = {The mixed-valent compound RBaCo4O7 (R=Rare earth, Y), hereafter abbreviated as R-114, is built up of Kagome sheets of CoO4 tetrahedra, linked in the third dimension by a triangular layer of CoO4 tetrahedra in an analogous fashion to that found in the known geometrically frustrated magnets such as pyrochlores and SrCr9xGa12-9xO19 (SCGO). We have undertaken a study of the structural and magnetic properties of the Y-114 and Yb-114 compound using combined high resolution powder neutron and synchrotron X-ray diffraction. Both compounds undergo a first order trigonal {yields} orthorhombic phase transition that breaks the trigonal symmetry of the structure. We show from Bond Valence Sum arguments that this transition occurs as a response to a markedly underbonded Ba2+ site in the high-temperature phase. The symmetry-lowering transition relieves the geometric frustration of the structure, and a long-range ordered 3-D antiferromagnetic state develops at low temperature. The magnetic structure of the Y compound has been solved and shows a compromise between the well-known 120o structure of the Kagome net and a collinear antiferromagnet in the third dimension.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

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