Spin-dependent extended x-ray absorption fine structure in magnetic oxides

The spin-dependent extended x-ray absorption fine-structure (EXAFS), i.e., the magnetic counterpart to the conventional EXAFS when using circularly po larized light in a ferro(i)magnet, was measured at the L-2,L-3 edges of Eu in Eu3Fe5O12 and EuO and at the K edge of CrO2. Complementary near-edge x-r ay magnetic circular dichroism measurements at the O K edge were made to di rectly access the oxygen magnetization. It is shown that there is an influe nce of the nearly nonmagnetic oxygen atoms on the magnetic EXAFS depending on the local symmetry of the crystal as well as on the relative direction o f the magnetic moments of neighboring atoms. The observed influences at dis tances corresponding to the oxygen neighbors in EuO are interpreted as the harmonic focusing effect, i.e., over-next magnetic neighbors behind the oxy gen are responsible for the observed contributions. (C) 1998 American Insti tute of Physics. [S0021-8979(98)51811-7].