Short-range spin order and frustrated magnetism in Mn_2InSbO _6 and Mn_2ScSbO_6

摘要

The complex metal oxides Mn_2ASbO_6 (A = In, Sc) with a corundum-related structure A_3BO_6 were prepared as polycrystalline powders by a solid-state reaction route. Their crystal structure and magnetic properties were investigated by using a combination of X-ray and neutron powder diffraction, electron microscopy, calorimetric, and magnetic measurements. At room temperature, these compounds adopt a trigonal structure, space group R? 3, with a = 8.9313(1) ?, c = 10.7071(2) ? (for In) and a = 8.8836(1) ?, c = 10.6168(2) ? (for Sc), which persists down to 1.6 K. The Mn and A cations were found to be randomly distributed over the A sites. The overall behavior of the magnetization of Mn _2InSbO_6 and that of Mn_2ScSbO_6 are quite similar. In spite of the relatively large amount of Mn ions on the A site, only short-range magnetism is observed. Neutron diffraction patterns of Mn _2InSbO_6 showed no evidence of a long-range magnetic ordering at 1.6 K, instead only a weak diffuse magnetic peak was observed at low temperatures. The factors governing the observed structural and magnetic properties of Mn_2ASbO_6 are discussed and compared with those of other Mn-containing complex metal oxides with a corundum-related structure. The influence of the A cation sublattice on the magnetic properties is also considered. The crystal structure and magnetic properties of Mn _2InSbO_6 and Mn_2ScSbO_6 were investigated by using a combination of X-ray and neutron powder diffraction, electron microscopy, calorimetric, and magnetic measurements.