K-edge resonant x-ray magnetic scattering from CoO

We report the observation of two contributions to resonant x-ray magnetic s cattering experiments performed at the K edge of Co in the antiferromagnet CoO. By using polarization analysis of the scattered x-ray beam, the two re sonances have been clearly associated to a quadrupolar resonance (1s-->3d) and a dipolar resonance (1s-->4p), respectively. The quadrupolar resonance is related to the magnetization of the 3d bands and to the existence of a n et orbital moment, whereas the dipolar resonance must be related to spin-or bit splitting of the (empty) Co 4p states. [S0163-1829(99)50538-9].