An electronic structure study of La 8− xSr xCu 8O 20− δ (8820) single crystal using polarized X-ray absorption spectroscopy

Abstract

Cu L 3 and O K edge polarised X-ray absorption spectroscopy has been employed to study a three-dimensional oxygen deficient perovskite single crystal of La 8− x Sr x Cu 8O 20− δ (8820) ( x=1.56) for E// a, E// b and E// a^45 polarizations. A careful analysis of the data shows an unmistakable presence of the itinerant e g( x2– y2) holes in it. The density of itinerant holes increases slightly as we move from E// a to the E// b orientation. This behaviour seems to be similar to the charge aggregation taking place along b-direction in an under-doped YBCO crystal in the normal state but it is rather strange as this system does not become superconducting on further cooling. This intriguing behaviour warrants further investigation.