Local defect structure of Sr{sub 3}Co{sub 2}O{sub x} (5.64{<=}x{<=}6.60): Evolution of crystallographic and magnetic states

Journal Article · Wed Nov 01 04:00:00 EST 2006 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.74.174417· OSTI ID:20853859

Hill, J M; Mitchell, J F; Jorgensen, J D ^[1]; Dabrowski, B ^[2]

---

1. Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
2. Department of Physics, Northern Illinois University, DeKalb, Illinois 60115 (United States)

We have extended the structural and magnetic phase diagrams of the bilayer Ruddlesden-Popper phase Sr{sub 3}Co{sub 2}O{sub x} beyond previously reported limits of x{approx_equal}6.1 to x=6.60. The room temperature crystal structure for the x=6.60 material is orthorhombic with oxygen vacancies located in the apical position that links the two nominally CoO{sub 2} layers in the perovskite block. An antiferromagnetic ground state is converted to ferromagnetic by moderate magnetic fields and high-temperature magnetic susceptibility data indicate short-range ferromagnetic order. We have also studied the oxygen defect structure of Sr{sub 3}Co{sub 2}O{sub x} in the range 5.64{<=}x{<=}5.80. Oxygen vacancies are present in both the in-plane sites, as well as the linking apical site. Critically, this linking site is displaced significantly along z from its ideal position, creating a particularly short Co-O bond. Using a combination of neutron powder diffraction (NPD) data and crystal-chemical considerations, we provide a model of the local Co ion environments. Additionally, low-temperature NPD and magnetization data show that the magnetic ground state of these oxygen-deficient materials is a complex antiferromagnet, with considerable sensitivity to precise oxygen content.

• OSTI ID: 20853859
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 17 Vol. 74; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANTIFERROMAGNETIC MATERIALS
ANTIFERROMAGNETISM
COBALT IONS
COBALT OXIDES
CONCENTRATION RATIO
CRYSTALS
FERROMAGNETIC MATERIALS
GROUND STATES
LAYERS
MAGNETIC FIELDS
MAGNETIC SUSCEPTIBILITY
MAGNETIZATION
NEUTRON DIFFRACTION
ORTHORHOMBIC LATTICES
OXYGEN
PHASE DIAGRAMS
STRONTIUM COMPOUNDS
VACANCIES