Spin density in YTiO3: I. Joint refinement of polarized neutron diffraction and magnetic x-ray diffraction data leading to insights into orbital ordering

Orbital ordering below 30 K was previously observed in the ferromagnetic YTiO3 compound both by polarized neutron diffraction (PND) and x-raymagnetic diffraction (XMD). In this paper we report a procedure for the joint refinement of a unique spin-density model based on both PND and XMDdata. The distribution of the unpaired 3d electron of titanium is clearly seen on the magnetization density reconstructed by the maximum entropy method from the PND data collection at 5 K. The Ti3+ 3d orbital populations obtained by joint model refinement are discussed in terms of the orbital ordering scheme. Small but significant magnetic moments on apical oxygen O-1 and yttrium atoms are found. The agreement between experimental and theoretical spin densities obtained using density functional theory is discussed.