Abstract
The structure and magnetic properties of orthorhombic Dy2TiO5 have been investigated using X-ray diffraction, neutron diffraction, and a.c./d.c. magnetic susceptibility measurements. We report a continuous structural distortion below 100 K characterized by negative thermal expansion in the [0 1 0] direction. Neutron diffraction and magnetic susceptibility measurements revealed local magnetic ordering begins at 3.1 K which followed by a 2D-3D magnetic transition at 1.7 K. The magnetic structure has been solved through a representational analysis approach and can be indexed with the propagation vector k = [0 ½ 0]. The spin structure corresponds to a coplanar model of interwoven two-dimensional “sheets” extending in the [0 1 0] direction. The local crystal field is different for each Dy3+ ion (Dy1 and Dy2), one of which possesses strong uniaxial symmetry indicative of Ising-like magnetic ordering. Consequently, two succeeding transitions under magnetic field are observed in the ac magnetization which are associated with flipping each Dy3+ spin independently.
