Non-stoichiometry and the magnetic structure of Sr2CrO3FeAs

Abstract

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 T_N = 36 K with a magnetic propagation vector of q = (1/2, 1/2, 0). The Cr3+ ions form a collinear magnetic structure of the C-type in the magnetic space group C_Pmma' (a' = a-b, b'=a+b, c'=c), where Cr3+-ions occupy the 4g (0, 1/4, 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 mu_B for the Cr3+-sublattice was refined.

6 pages, 6 figures

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Cited by in corpus (12)

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• Self doping effect and successive magnetic transitions in superconducting Sr${}_2$VFeAsO${}_3$
• Crystal Chemistry and Structural Design of Iron-Based Superconductors
• Physical properties and electronic structure of Sr${}_2$Cr${}_3$As${}_2$O${}_2$ containing CrO${}_2$ and Cr${}_2$As${}_2$ square-planar lattices
• Magnetic Ordering in Blocking Layer and Highly Anisotropic Electronic Structure of High-Tc Iron-based Superconductor Sr2VFeAsO3: LDA+U Studies
• Suppression of superconductivity by V-doping and possible magnetic order in Sr2VO3FeAs
• Formation of the density wave energy gap in Na${}_2$Ti${}_2$Sb${}_2$O: an optical spectroscopy study
• Magnetic Ordering in V-Layers of the Superconducting System of Sr2VFeAsO3
• Static magnetic order of Sr${}_4$A${}_2$O${}_6$Fe${}_2$As${}_2$ (A = Sc and V) revealed by local probes
• Superconducting transition temperatures in the electronic and magnetic phase diagrams of Sr2VFeAsO3-delta, a superconductor
• Electronic properties of new low-temperature superconductors: 3.3K (Ni2P2)(Sr4Sc2O6) and 2.7K (Ni2As2)(Sr4Sc2O6) from first principles
• Absence of itinerant ferromagnetism in a cobalt-based oxypnictide