Short-range Magnetic Ordering in the Geometrically Frustrated Layered Compound YBaCo4O7 with an Extended Kagomé Structure

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Structural and magnetic properties of the geometrically frustrated layered compound YBaCo4O7 have been studied by magnetization and neutron diffraction. A layered type crystal structure, with alternating tetrahedral layers of Kagomé and triangular types, along the c axis (hexagonal symmetry, space group P63mc) has been found. The oxygen content of the present compound was determined by iodometric titration to be 7.00±0.01. Presence of a short-range antiferromagnetic ordering (below TN 110 K) has been concluded from the appearance of an addition broad magnetic peak (at Q 1.35 Å-1) in the neutron diffraction pattern. A staggered chiral type (√3 √3) spin structure in the Kagomé layers has been found. Presence of a significant magneto-structural coupling is concluded from the changes in lattice parameters across the magnetic ordering temperature TN 110 K.