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Jülich Centre for Neutron Science 
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DNS |
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Local contact: |
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Yixi Su|
Neutron polarization analysis reveal spin correlations in Sr2CrO3FeAs |
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A group of scientists of the Department of Chemistry at Ludwig-Maximilians-University Munich and the Jülich Center of Neutron Science have revealed evidence of certain spin correlations in the strontium chromate iron arsenide compound by polarised neutron diffraction. The work has been published in a recent issue of Europhysics Letters, Vol 89, 37006 (2010). |
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Led by D. Johrendt Sr2CrO3FeAs was synthesized and investigated by neutron powder diffraction at the ILL neutron diffractometer D20. Separation of nuclear coherent, spin incoherent and magnetic scattering contributions were obtained by neutron polarisation analysis at the diffuse scattering diffractometer DNS at JCNS at FRM II. A mixed occupancy of chromium and iron in the FeAs layers was found. The authors suggest that the Cr-doping may be the reason for the absence of a SDW anomaly and superconductivity. Such non-stoichiometries may also occur in similar compounds like the superconducting Sr2VO3FeAs and may also be responsible for the different physical behavior of these compounds when compared with the 1111- and 122-iron arsenides. Deviations from the ideal stoichiometry has especially to be taken into account when discussing their electronic structures. Sr2CrO3FeAs shows short-range spin correlations from the Cr3+-ions below 100K and long-range antiferromagnetic ordering below T(N) =36.0(5) K. The magnetic structure is of the C-type with the Cr-spins oriented parallel to a-b axis with all nearest-neighbor Cr3+ moments antiferromagnetically aligned, thus forming a checkerboard arrangement. |
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last change 02.03.2010 | jcns@fz-juelich.de jcns | Print