Volume 89, Number 3, February 2010
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||23 February 2010|
Non-stoichometry and the magnetic structure of Sr2CrO3FeAs
Department Chemie, Ludwig-Maximilians-Universität München - Butenandtstraße 5-13 (Haus D), 81377 München, Germany, EU
2 Jülich Centre for Neutron Science, IFF, Forschungszentrum Jülich, Outstation at FRM II Lichtenbergstraße 1, D-85747 Garching, Germany, EU
3 Jülich Centre for Neutron Science, Forschungszentrum Jülich, Outstation at Institut Laue-Langevin BP 156, 38042 Grenoble Cedex 9, France, EU
4 Institut Laue-Langevin - BP 156, 38042 Grenoble Cedex 9, France, EU
Corresponding author: email@example.com
Accepted: 19 January 2010
The iron arsenide Sr2CrO3FeAs with the tetragonal Sr2GaO3CuS-type structure was synthesized and its crystal structure re-determined by neutron powder diffraction. In contrast to previous X-ray crystallographic studies, a mixed occupancy of chromium and iron was found within the FeAs4/4 layer (93±1%Fe:7±1%Cr). We suggest that the partial Cr-doping at the Fe site is the reason for the absence of a spin-density-wave anomaly and superconductivity in this compound. Additional experiments via neutron polarization analysis revealed short-range spin correlations below ~ 100 K and long-range antiferromagnetic ordering below TN = 36 K with a magnetic propagation vector of q = (, , 0). The Cr3+-ions form a collinear magnetic structure of the C-type in the magnetic space group (a' = a-b, b' = a+b, c' = c), where Cr3+-ions occupy the 4g (0, , z ) Wyckoff position. The magnetic moments are aligned along the orthorhombic a'-axis. At 3.5 K, an ordered magnetic moment of 2.75±0.05 for the Cr3+-sublattice was refined.
PACS: 74.10.+v – Occurrence, potential candidates / 61.05.fm – Neutron diffraction / 75.50.Ee – Antiferromagnetics
© EPLA, 2010
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