Journal Article

PreJuSER-20465

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Spin correlation in the extended kagome system YbaCo3FeO7

Valldor, M. ; Hermann, R.FZJ* ; Wuttke, J.FZJ* ; Zamponi, M.FZJ* ; Schweika, W.FZJ*

2011
APS College Park, Md.

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Please use a persistent id in citations: http://hdl.handle.net/2128/10866  doi:10.1103/PhysRevB.84.224426

Abstract: The transition metal-based oxide YBaCo3FeO7 is structurally related to the mineral Swedenborgite SbNaBe4O7, a polar noncentrosymmetric crystal system. The magnetic Co3Fe sublattice consists of a tetrahedral network containing kagome-like layers with trigonal interlayer sites. This geometry causes frustration effects for magnetic ordering, which were investigated by magnetization measurements, Mossbauer spectroscopy, polarized neutron diffraction, and neutron spectroscopy. Magnetization measurement and neutron diffraction do not show long range ordering even at low temperature (1 K), although a strong antiferromagnetic coupling (similar to 2000 K) is deduced from the magnetic susceptibility. Below 590 K we observe two features, a spontaneous weak anisotropic magnetization hysteresis along the polar crystallographic axis and a hyperfine field on the Fe kagome sites, whereas the Fe spins on the interlayer sites remain idle. Below similar to 50 K the onset of a hyperfine field shows the development of moments static on the Mossbauer time scale also for the Fe interlayer sites. Simultaneously, an increase of spin correlations is found by polarized neutron diffraction. The relaxation part of the dynamic response has been further investigated by high-resolution neutron spectroscopy, which reveals that the spin correlations start to freeze below similar to 50 K. Monte Carlo simulations show that the neutron scattering results at lower temperatures are compatible with a recent proposal that the particular geometric frustration in the Swedenborgite structure promotes quasi-one-dimensional partial order.

Keyword(s): Basic research (1st) ; Others (1st) ; Magnetism (2nd) ; J

Note: We are grateful for comments from Daniel Khomskii and Gary J. Long. Moulay Sougrati is acknowledged for assisting in the collection of the Mossbauer spectral data. We would like to thank Anne Mochel for help in measuring magnetic susceptibility of the isotope-enriched sample. This work was supported by DFG through the project SFB 608, by the FNRS through Grants No. 9.456595 and 1.5.064.5, and by the Helmholtz Association of German Research Centers through Grant No. NG-407. Part of this research at the instrument BASIS Oak Ridge National Laboratories Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy.

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Contributing Institute(s):

1. Streumethoden (PGI-4)
2. Streumethoden (JCNS-2)
3. Jülich-Aachen Research Alliance - Fundamentals of Future Information Technology (JARA-FIT)
4. JCNS-FRM-II (JCNS (München) ; Jülich Centre for Neutron Science JCNS (München) ; JCNS-FRM-II)

Research Program(s):

1. Grundlagen für zukünftige Informationstechnologien (P42)

Experiment(s):

1. DNS: Diffuse scattering neutron time of flight spectrometer (NL6S)
2. SPHERES: Backscattering spectrometer (NL6S)

Appears in the scientific report 2011

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