ALTERED SR ENVIRONMENT IN LA2-XSRXCUO4

The atomic arrangement about the Sr atoms in La2-xSrxCuO4 was investig ated by Sr K-edge polarized x-ray-absorption fine structure on oriente d powder with x=0.075 and 0.1 at T=20 K. Our results confirm that Sr r esides at the La lattice site but we discovered it induces major struc tural distortions in neighboring oxygen atoms. In particular, our best fits indicate that the O(2) apical oxygen to Sr is split into two sit es separated by 0.30(4) Angstrom, providing evidence for a strong latt ice-hole interaction, i.e., a polaron, which may be involved in the pa iring mechanism of these cuprates.