Thermal Evolution of the Crystallographic and Magnetic Structure in LuVO3: A Neutron Diffraction Study

Abstract

Polycrystalline LuVO 3 perovskite has been studied by neutron powder diffraction (NPD), specific heat, and magnetization measurements. Below T N 107 K, LuVO 3 undergoes magnetic ordering according to a canted antiferromagnetic structure. Neutron diffraction data show that the magnetic structure is characterized by the propagation vector k = 0 and the spin arrangement for the V atoms below T N is given by the basis vector (0,A y ,F z ). The magnetic structure remains stable down to 2 K and the ferromagnetic component is very weak, in good agreement with the magnetic measurements. The ordered magnetic moment at T = 2.4 K for the V atoms is 1.33(6)μ B . A few degrees below T N , a crystallographic transition is observed, from the orthorhombic room-temperature structure (Pnma space group) to monoclinic (P2 1 /n space group) below the transition. The changes in the crystallographic structure occur between 94 and 82 K. Despite the fact that below 82 K there are two sites for the V atoms, the arrangement of the V-O bonding lengths is the same in the y = 0 plane and in the y = 1/2 layer, so the (010) planes are in phase along the b-direction. This suggests an in-phase orbital ordering of the V t 2g orbitals compatible with the A-type magnetic structure.