Magnetic Structure of YBaCo₄O₇with Kagome and Triangular Lattices

Abstract

Neutron diffraction studies have been carried out in the temperature(T) range\nbetween 10 K and 130 K on a single crystal of YBaCo4O7, which has the stacking\nof kagome and triangular lattices of CoO4 tetrahedra along the c-axis.\nStructural transitions have been found at two temperatures Tc1~70 K and Tc2~105\nK. With decreasing T, magnetic order appears along with the transition at Tc2,\nbut it does not grow to an ideal long-range order even at the lowest T studied\n(~10 K). Two groups of magnetic diffuse reflections, which originate from the\nCo-moments of the kagome and triangular lattices, are observed separately in\nthe reciprocal space. With further decreasing T, the growth rates of the\nintensities of these two are enhanced by another transition at Tc1. These\nmagnetic behaviors seem to be related to the release of the geometrical\nfrustration. At 10 K, the patterns of the magnetic short-range order have been\ndetermined for both sites of the kagome and triangular lattices.\n