Synchrotron X-ray study of the electron density in RFeO3 (R = Nd, Dy).

Structure factors for small hydrothermally grown orthorhombic neodymium and dysprosium iron oxides RFeO(3) (R = Nd, Dy) were measured with focused lambda = 0.84 Å synchrotron radiation using a fast avalanche photodiode (APD) counter. Higher symmetry in the deformation electron density (Deltarho) maps reflects the coordination of the magnetic atoms in the structure and implies that Deltarho is sensitive to the cation-cation magnetic interactions. Within a given compound the local Deltarho topographies around the R and Fe atoms are similar, but differ markedly between compounds. The difference in Deltarho near the Nd and Dy atoms is associated with the different type of spin reorientation transitions in these compounds. The R-Fe magnetic interactions determine the magnetic phase transitions and consequently affect the electron distribution. Synchrotron radiation diffraction imaging of the electron density provides an additional tool for probing the magnetic properties of materials.