POLARIZED X-RAY O K-EMISSION AND CU L-EMISSION BANDS OF YBA2CU3O6 AND YBA2CU3O7-DELTA

Polarized O K- and Cu L-emission bands measured at take-off angles 15-degrees and 70-degrees are presented for YBa2Cu3O6 and YBa2Cu3O7-delta. A considerable angular dependence of the intensity is observed for both the O K- and Cu L-emission bands of superconducting YBa2Cu3O7-delta, while the radiation of the O K-emission band of YBa2Cu3O6 is almost isotropically emitted and only a small polarization effect is observed for the Cu L-emission band. The origin of the angular dependence of the X-ray emission bands of both samples is analyzed and the role of oxygen p-like and copper d-like electrons is discussed. Our experimental results indicate that the top of the valence band of YBa2Cu3O7-delta is formed by oxygen p(x) and p(y) electrons.