Journal of Applied Physics · 1987 · 11 citations · 2 references
Natural SciencesMaterials SciencePhysicsCondensed Matter PhysicsCrystal StructureMagnetic MaterialsAntiferromagnetic MaterialsAntiferromagnetismMagnetic OxidesMagnetic Properties Of SolidsMagnetism In SolidsPhase TransitionsAntiferromagnetic OxidesInterchain InteractionsMagnetic Phase DiagramMagnetic Phase TransitionsMagnetic Space GroupsSpin OrderingUnit Cell ParametersUnit Cell Symmetry
Long-range spin ordering has been studied in the quasi-one-dimensional antiferromagnet α-FeC2O4⋅2D2O by neutron diffraction on a powdered sample above and below TN=11.7 K. Data at 14 K show essentially the room-temperature chemical structure. The space group is C2/c, Z=4, and unit cell dimensions are a=11.700 Å, b=5.568 Å, and c=9.847 Å with β=128.05°. Magnetic peaks appear at TN and data at 10.5 K show doubling of the unit cell along the b direction, the chain axis. The ordered structure belongs to the magnetic space group P2b2/n with spins parallel to the b axis. Cancellation of certain interchain interactions gives the structure a pronounced two-dimensional character. At T2=9.5 K a discontinuous transition to a second magnetic phase occurs with additional doubling of the unit cell in the a direction. Below T2 the symmetry of the magnetic structure is reduced to triclinic, P2s1̄ with the spins deviating slightly from the b axis.
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