Structure and Magnetic Properties of Dy2Mn4O9

Single crystals of Dy2Mn4O9, a new rare-earth transition metal oxide, were grown by a three-component flux method. X-ray studies indicate that the space group of this crystal is Pbam and the dimensions of the orthorombic unit cell are; a=7.24, b=8.44, c=5.62 Å. Magnetization measurements at 1.3° to 300°K in a magnetic field of 14.2 kOe show that an antiferromagnetic transition takes place in Dy2Mn4O9 at about 8°K. Large magnetic anisotropy is observed, the easy direction of magnetization lying along the a axis. At 4.2°K in a field of 100 kOe the magnetization along the c axis is less than 50% of that along the a-axis. In Mössbauer studies of the 26-keV γ-transition in 161Dy typical paramagnetic relaxation spectra were observed, from which the ``g'' tensor of the ground stark level of the Dy3+ ions was deduced; gz=18.5gx≈0, gy≈0. The spin-relaxation time of the Dy ions at 5°K was estimated to be 2×10−9 sec.